Pregnancy in women with mitral stenosis

INTRODUCTION — Mitral stenosis (MS) encountered in women of childbearing age is nearly always rheumatic in origin. Maternal and perinatal complications during pregnancy in women with MS reflect the unfavorable interaction between the normal cardiovascular changes of pregnancy and the stenotic mitral valve. (See "Maternal adaptations to pregnancy: Cardiovascular and hemodynamic changes".)

This topic will review the evaluation and management of women with MS during pregnancy. Management of other types of heart disease during pregnancy, including those with MS who have undergone valve replacement, is discussed separately. (See "Acquired heart disease and pregnancy" and "Pregnancy in women with congenital heart disease: Specific lesions" and "Pregnancy in women with congenital heart disease: General principles" and "Management of antithrombotic therapy for a prosthetic heart valve during pregnancy".)

PREVALENCE — Women with heart disease comprise approximately 1 percent of the obstetric population seen in large volume centers in developed countries. In the United States and Canada, women with rheumatic heart disease, of which MS is the most common manifestation, comprise <25 percent of the pregnant women with heart disease [1,2]. Similarly, among 2966 women with heart disease included in the international Registry on Pregnancy and Cardiac disease (ROPAC), 390 women had rheumatic mitral valve disease, of which 273 (9 percent) had MS [3].

In contrast, MS is a common condition in pregnant women with heart disease in other areas of the world where rheumatic heart disease is prevalent. For example, rheumatic heart disease was the underlying cause in 56 to 88 percent of women in four studies from centers from Brazil, Turkey, Senegal, and India reporting on a total of 2601 pregnancies in women with heart disease [4-7]. (See "Clinical manifestations and diagnosis of rheumatic heart disease", section on 'Mitral stenosis'.)

IMPACT OF CARDIOVASCULAR CHANGES IN PREGNANCY IN WOMEN WITH MITRAL STENOSIS — In MS, the stenotic mitral valve restricts diastolic left ventricular filling, resulting in an elevated transmitral gradient and left atrial pressure that are further increased by the physiologic hypervolemia and increased heart rate during pregnancy, thereby increasing the risk of pulmonary congestion or pulmonary edema (figure 1). The risk of pulmonary congestion remains during labor and delivery, as a result of uterine contraction during labor, and with the autotransfusion of venous return from the lower extremities as the emptied uterus is no longer impeding venous return redistribution pulmonary edema may occur. Increased atrial irritability and hypercoagulability associated with pregnancy, when combined with increased left atrial pressure, increase the risk of atrial fibrillation and left atrial thrombus formation. (See "Maternal adaptations to pregnancy: Cardiovascular and hemodynamic changes" and "Deep vein thrombosis in pregnancy: Epidemiology, pathogenesis, and diagnosis".)

RELATIONSHIP BETWEEN SEVERITY OF MS AND IMPACT OF PREGNANCY — There is a direct relationship between the severity of MS and the risk of maternal and/or fetal complications [8-10] (see "Pathophysiology and natural history of mitral stenosis" and "Echocardiographic evaluation of the mitral valve"). There is an incremental increase in the frequency of maternal and fetal complications with increasing severity of MS (table 1). While those with moderate or severe stenosis represent the higher risk group, elevated event rates are seen in those with even mild MS, reflecting the effects of the 30 to 50 percent increase in cardiac output superimposed on a mildly stenotic valve [1]. History of cardiac complications (including pulmonary edema, arrhythmias, transient ischemic attacks, or stroke) prior to pregnancy and poor baseline maternal functional class are additional risk factors for maternal cardiac complications during pregnancy [1,10]. In the presence of obstetric risk factors (including extremes of maternal age, smoking), the presence of maternal MS confers a risk of perinatal complications [11].

NATURE AND FREQUENCY OF ADVERSE PREGNANCY OUTCOMES — A summary of maternal and fetal outcomes stratified by severity of mitral stenosis are provided in the table (table 1). Risk estimates for mild MS were pooled from three case series [8,10,12]. Risk estimates corresponding to moderate or severe MS are from a systematic review that included these three studies [13].

Maternal outcomes — Adverse maternal outcomes are more common in low and middle income countries. In the four largest contemporary series from North America and Europe of pregnant women with MS (total of 300 pregnancies), there were no maternal deaths [6,8-10]. In contrast, studies from low and middle income countries have found significant risk of maternal death. In two studies of 661 pregnancies in women with MS mostly from low to middle income countries, there were 11 deaths occurring in patients with severe MS (6 percent) [7,12]. In a study of 46 pregnant women with MS from sub-Saharan Africa, the maternal mortality rate was even higher at 32 percent [5]. While women with moderate or severe MS are at the highest risk for maternal and fetal events, those with mild MS are still at risk for heart failure, arrhythmia, and fetal complications (table 1) [8,10,12].

While women with predominant mitral regurgitation are commonly viewed as being at lower risk than those with MS, a 15 percent rate of heart failure has been reported in those with moderate or severe mitral regurgitation [12]. For prediction of maternal cardiac risk, moderate to severe mitral regurgitation is considered equivalent to mitral stenosis [14].

Pregnant women with MS are at risk for pulmonary edema and atrial arrhythmias (table 1). As discussed above, cardiovascular changes during pregnancy result in an increase in the transmitral gradient and increased left atrial pressure, which in turn increases pulmonary venous pressure, placing pregnant women with MS at risk for pulmonary congestion. In the two series from ROPAC and India, up to 91 percent of heart failure episodes first occurred in the antepartum period, and up to 29 percent occurred during delivery or the first postpartum week [7,12]. This observation parallels the finding of a prospective Canadian study of pregnant women with a wide spectrum of heart disease, in which there were two peaks of incidence of heart failure in the third trimester (28 to 40 weeks gestation) and in the first postpartum week, corresponding to the peak hemodynamic load during the late antepartum period and the time of postpartum fluid redistribution [14].

The risk of atrial fibrillation also increases during pregnancy, which in turn can precipitate pulmonary edema. Although atrial fibrillation is the most common arrhythmia encountered, other supraventricular arrhythmias can be manifested, including atrial flutter and supraventricular tachycardia. Pulmonary congestion and atrial fibrillation can become a self-perpetuating vicious cycle, and it is not always clear which was the precipitating factor. In contrast to heart failure, which peaks in the third trimester and the postpartum period, cardiac arrhythmia can occur anytime in the ante-, peri-, or postpartum period [14]. In one series, 20 percent of the pulmonary edema episodes occurred in the setting of atrial tachyarrhythmias [10]. (See "Supraventricular arrhythmias during pregnancy".)

Only one stroke was reported in the above cited North American and European series [6,8-10], perhaps due to increased vigilance and prompt initiation of anticoagulation. In the above cited series from an early study from Brazil, eight episodes of thromboembolism occurred in 448 patients with native mitral valves [4].

Even when pregnancy is not complicated by the development of pulmonary edema, some women with MS experience deterioration in their functional class or develop new cardiac symptoms. In two North American series (total of 126 pregnancies), 74 and 40 percent of women experienced deterioration of one and two New York Heart Association (NYHA) functional classes, respectively, as their pregnancies progressed [8,10]. If not promptly diagnosed and treatment initiated, women who deteriorated to NYHA class III or IV will likely progress to frank pulmonary edema.

Fetal outcomes — Perinatal complications, which include premature labor, low fetal weight, fetal complications of prematurity, and perinatal death, are generally increased in women with heart disease and are more frequent with increasing severity of MS (table 1) [8,10,12,13].

EVALUATION — Prepregnancy counseling should be offered to all females with MS who are of child-bearing age. In those patients who do not present until they are pregnant, counseling should be performed as early in pregnancy as possible. The purposes of prepregnancy or pregnancy counseling are to provide risk assessment, risk reduction, and management planning to optimize risk or mitigate effects of complications (table 2).

Counseling should be preferably provided by a cardiac-obstetric or pregnancy heart team that includes, at a minimum, a cardiologist with expertise in management of pregnancy in women with heart disease and an obstetrician with expertise in maternal fetal medicine [15]. A careful cardiac history and physical examination, 12 lead electrocardiogram (ECG), and a comprehensive transthoracic echocardiogram will provide the information necessary for the management of the woman with MS who is either pregnant or is contemplating pregnancy. Exercise testing (including cardiopulmonary or exercise echocardiography) is useful to assess objective exercise tolerance and to assess pulmonary artery pressure during exercise. (See "Rheumatic mitral stenosis: Overview of management" and "Acquired heart disease and pregnancy".)

RISK STRATIFICATION — Women at highest risk of maternal cardiac complications are those with moderate or severe MS (mitral valve area ≤1.5 cm²), baseline maternal New York Heart Association functional class III or IV, a history of cardiac complications (pulmonary edema, arrhythmias requiring treatment, transient ischemic attack, or stroke) prior to pregnancy, central cyanosis, left ventricular systolic dysfunction, and pulmonary hypertension [8-10,14].

Women with MS considering pregnancy should also be assessed by an obstetrician with expertise in medical disorders of pregnancy, to allow for an expert assessment of markers of obstetric risk and to address the obstetric aspects of management. Women with moderate or severe MS are at greatest risk of fetal neonatal complications such as perinatal death, premature delivery, low birth weight, or complications of prematurity (table 1). Obstetric complications such as pregnancy induced hypertension and antepartum hemorrhage have been reported but do not seem to be related to the severity of MS [1,10,12].

CLINICAL MANAGEMENT

Preconception counseling and management — Evaluation prior to preconception counseling includes identification of any markers of increased maternal cardiac risk as determined by history, examination, ECG, transthoracic echocardiogram, and exercise testing (including exercise echocardiography) as described above (see 'Risk stratification' above):

●History of pulmonary edema, arrhythmias requiring treatment, transient ischemic attack, or stroke prior to pregnancy.

●Functional status by subjective (ie, New York Heart Association functional class) or objective measures (exercise testing).

●Central cyanosis (oxygen saturation <90 percent by oximetry).

●Mitral valve area, extent of mitral regurgitation, left ventricular systolic function.

●Systolic pulmonary artery pressure.

Risk stratification can be performed either with the updated Canadian Cardiac Disease in Pregnancy (CARPREG II) risk score or the modified World Health Organization classification system [14,16]. Regardless of the risk-prediction tools chosen, risk can be upgraded or downgraded based on the clinician’s assessment of compliance, access, and other test results, such as exercise test results [15].

It is important to note that American Heart Association/American College of Cardiology (AHA/ACC) valve disease guidelines and European Society of Cardiology (ESC) guidelines for cardiovascular disease during pregnancy have defined mitral valve area ≤1.5 cm² as "severe" (AHA/ACC since 2014) or "clinically significant" (ESC in 2018) MS [16-18]. This criterion for severe MS includes a mitral valve area of 1.1 to 1.5 cm², which was considered to be moderate MS in earlier outcome studies.

At the time of prenatal counseling, attention should be paid to smoking history and the use of medications that may be potentially teratogenic. Cessation of smoking prior to conception would reduce the risk of perinatal complications. Angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARB) are contraindicated during pregnancy and should be discontinued prior to pregnancy [19] (see "Adverse effects of angiotensin converting enzyme inhibitors and receptor blockers in pregnancy"). Women who are receiving warfarin therapy should have the opportunity to make an informed decision about the various options for anticoagulation so that the anticoagulation plan can be implemented once pregnancy is confirmed. (See "Use of anticoagulants during pregnancy and postpartum" and "Prenatal care: Initial assessment".)

The 2018 ESC guidelines recommend that patients with significant MS should be counseled against pregnancy, and intervention should be considered prior to pregnancy, especially if mitral valve area is <1 cm² [16]. While termination of pregnancy is an option if a woman with mitral valve area <1 cm² presents early in pregnancy, this decision is individualized based upon the patient’s preference with consideration of access to care, functional status, and other pregnancy risk factors.

While data are not available for patients with MS, women considering artificial reproductive technology to achieve conception should be aware of the increased risk of maternal cardiac and neonatal complications associated with these procedures [20].

Indications for preconception intervention — Valve intervention prior to conception is recommended in women with significant (moderate or severe MS; mitral valve area ≤1.5 cm²) who are symptomatic or have reduced exercise capacity [17,21]. Percutaneous mitral valvuloplasty performed in an experienced center is the intervention of choice, assuming that valve morphology is suitable and there are no contraindications (such as left atrial or left atrial appendage thrombus). (See "Percutaneous mitral balloon commissurotomy in adults".)

The 2021 ACC/AHA valvular heart disease guideline notes that preconception percutaneous mitral balloon commissurotomy at a Comprehensive Valve Center is reasonable for asymptomatic patients with mitral valve area ≤1.5 cm² who have favorable valve morphology for percutaneous balloon commissurotomy [18]. The 2018 ESC guidelines recommended that asymptomatic women with moderate or severe MS should avoid pregnancy and undergo prepregnancy intervention, favoring a percutaneous approach [16]. These recommendations, based on expert consensus or observational studies, may not be applicable in women with access to specialty care, normal exercise tolerance, are not at high thromboembolic risk, and who do not have pulmonary artery hypertension.

In asymptomatic women with moderate or severe MS and normal pulmonary artery pressure, we recommend exercise testing to determine whether exercise capacity is normal and to evaluate for the presence of exercise induced pulmonary hypertension. We suggest not routinely intervening in women with moderate or severe MS who are asymptomatic with normal pulmonary artery pressure and excellent exercise capacity. However, in situations where patient compliance is an issue, or where there are barriers to provision of timely antenatal care or urgent percutaneous valvuloplasty, then there is a compelling reason to recommend elective percutaneous intervention for asymptomatic women with moderate to severe MS prior to pregnancy.

Antepartum — With appropriate care including judicious use of beta blockers and/or diuretics, most women with MS can undergo pregnancy without the need for invasive interventions. Intervention during pregnancy (preferably by percutaneous mitral balloon valvotomy) is reserved for those patients with severe symptoms despite maximal medical therapy and hospitalization.

Monitoring — Women with MS should undergo cardiovascular assessment as early during pregnancy as possible, especially if there has been no opportunity for a prepregnancy assessment. The approach at the first antenatal visit is the same as for prepregnancy assessment, with additional attention to the cessation of medications that may be teratogenic, such as ACE inhibitors or ARBs. Patients with high risk features, such as significant or severe MS or pulmonary hypertension, should be discussed at a multidisciplinary conference involving obstetrics, cardiology, perinatology, nursing, and social work to ensure that there is a written plan for follow-up during the antepartum period and also for labor and delivery.

The frequency of cardiac follow-up during pregnancy will be determined by the risk level. The 2018 ESC guidelines recommend monthly or bimonthly follow-up for moderate to severe MS (mitral valve area ≤1.5 cm²), and at every trimester and prior to pregnancy for mild MS [16]. These are general guidelines, with some experts recommending biweekly follow up visits until 30 weeks gestation followed by weekly visits until delivery [22]. B-type natriuretic peptide level can be helpful if clinical assessment is inconclusive in the symptomatic patient. As pregnant women with MS will also be undergoing serial obstetric assessment, caregivers should consider establishing a combined cardiac-obstetric clinic where cardiac and obstetric assessment can be scheduled during the same clinic visit, reducing the need for travel for patients in whom functional deterioration is common as pregnancy advances. While there are no specific recommendations for echocardiographic assessments, at the minimum, an echocardiogram should be performed at the first antepartum visit and again during the third trimester visit. Transmitral gradient will increase as pregnancy progresses, but pressure half-time, planimetry, and continuity-equation are less preload-dependent methods to measure mitral valve area. Systolic pulmonary artery pressure may also increase.

At the time of each clinical assessment, history and signs of functional class deterioration, pulmonary congestion, and arrhythmias should be sought.

Medical management — Routine use of beta 1 selective blockers is recommended (avoiding atenolol since its use is associated with low birthweight). Heart rate goals for beta blocker therapy have not been established. Functional deterioration may be an early warning sign of impending heart failure and can be treated by a small dose of furosemide, restriction of activities, and beta blockers to reduce tachycardia and improve LV filling [23]. Digoxin can also be used but may be less effective in reducing heart rate than beta blockers, as renal clearance of digoxin is increased during pregnancy. Patients with pulmonary edema should be admitted to a hospital and treated with oxygen, intravenous furosemide, and introduction of beta blockers. (See "Management of heart failure during pregnancy".)

Anticoagulation is recommended in those with atrial fibrillation, left atrial thrombus, or prior embolism. In those with significant MS and in sinus rhythm, anticoagulation is a consideration if there is spontaneous echocardiographic contrast in the left atrium, large left atrium (>60 mL/m²), or heart failure [16].

Management of arrhythmias — Sustained or frequent palpitations should be promptly investigated. Atrial fibrillation and other supraventricular tachycardia should be treated to prevent deleterious effect on uteroplacental perfusion. The key considerations in treating atrial fibrillation in pregnant women with MS are prompt initiation of anticoagulation and rhythm control to prevent thromboembolic episodes and the risk of pulmonary edema. Low molecular weight heparin, or intravenous unfractionated heparin for hospitalized patients, is often used during pregnancy to avoid the potential teratogenicity and fetopathic effects of warfarin. Rate control with beta blockers or digoxin is the initial strategy for sustained atrial fibrillation. Beta blockers are more effective at heart rate control than digoxin as the renal clearance of digoxin is increased during pregnancy. As an elevated heart rate is crucial to maintain the augmented cardiac output in later pregnancy, the goal of ventricular rate control should be at 70 to 90 bpm rather than <60 bpm as in nonpregnant state. Electrical cardioversion should be considered when the ventricular rate or symptoms are responding poorly to rate control or when there is hemodynamic instability. If possible, transesophageal echocardiography should be performed prior to electrical cardioversion to exclude left atrial thrombus, which would be a contraindication to electrical cardioversion. Based on small case series, electrical cardioversion is considered to be safe for the fetus with a low risk of fetal distress, fetal arrhythmia, or preterm labor [16,24]. The fetal safety profile will need to be considered when choosing an antiarrhythmic agent for maintenance of sinus rhythm [8]. (See "Supraventricular arrhythmias during pregnancy" and "Rheumatic mitral stenosis: Overview of management", section on 'Management of atrial fibrillation'.)

Intervention — When intervention is required antepartum due to severe symptoms despite maximal medical therapy and hospitalization, the feasibility of percutaneous mitral balloon valvotomy (PMBV) should be assessed. Consultation with maternal-fetal medicine and neonatology specialists is essential in planning the timing of PMBV in order to weigh the maternal and fetal risks of continuing medical therapy versus the maternal and neonatal risks if emergency delivery is required. The procedure is best done after the period of organogenesis (>20 weeks) but prior to mid to late third trimester when the gravid uterus can interfere with catheter access and hemostasis with the femoral approach. PMBV may need to be performed earlier in pregnancy in those with refractory class IV symptoms or heart failure despite maximal medical therapy. Selection of a time for PMBV during pregnancy involves balancing competing risks, with involvement of the patient in the decision. If emergency delivery is required because of maternal compromise during the procedure, neonatal outcome generally improves with advancing gestational age. However, delaying the procedure until later in gestation increases the chances of maternal decompensation if MS is severe, and, in turn, increases the chances of emergency delivery which adversely affects maternal and fetal survival.

During PMBV, the radiation dose should be minimized by using abdominal shielding and keeping exposure times as short as possible. The fetal heart rate should be monitored continuously and assessed by an obstetric provider in case maneuvers for fetal resuscitation (eg, modification of maternal position, increased fluids, increased oxygenation) are indicated. Resources should be readily available for emergency cesarean delivery and care of a premature infant. Furthermore, the anesthetic management of the pregnant patient during PMBV involves additional considerations that have been reviewed [25]. (See "Percutaneous mitral balloon commissurotomy in adults".)

The efficacy of PMBV was evaluated in a study of 45 pregnant women who underwent PMBV or surgical mitral valve commissurotomy for severe heart failure [26]. The procedural success rate of PMBV was 95 percent. Improvement in symptoms was the same in both groups; however, fetal complications were less frequent and fetal and neonatal mortality were lower with PMBV (5 versus 38 percent with surgical commissurotomy).

The efficacy and safety of PMBV during pregnancy were evaluated in a single-center report of 30 patients undergoing PMBV [27]. Patients ranged in NYHA functional class from II to IV (only two being in class IV) with a mean pulmonary artery systolic pressure of 68±23 mmHg. Patients underwent PMBV during either the second (n = 16) or third trimester (n = 14). Wilkins score was greater than 8 in 11 women. The mean mitral valve area increased from 0.85±0.16 cm² to 1.60±0.27 cm² immediately after PMBV and only two patients had an increase in mitral regurgitation by two grades. All pregnancies ended with successful delivery of infants with no spontaneous abortions, still births, or neonatal deaths. On six-month follow-up of 27 infants, all had normal growth and mental development.

Open-heart mitral valve surgery is reserved for patients with refractory severe symptoms who are not candidates for (or fail to respond to) PMBV.

Two observational studies including pregnant women with MS as well as other heart lesions reported an association between antepartum cardiac complications and the frequency of premature labor [28,29]. This observation is pertinent to planning the timing of delivery for the women with MS who developed cardiac complications close to term.

Peripartum — A planned or induced delivery should be considered in women with MS with high risk features (moderate to severe MS, pulmonary hypertension, history of cardiac complications prior to or during pregnancy) or in those who live a considerable distance from the delivering hospital. With the use of regional anesthesia to attenuate the spikes in cardiac output during labor, almost all women with MS can undergo vaginal delivery with an assisted second stage. Caesarian delivery is reserved for obstetric indications and in whom anticoagulation cannot be reversed (see "Anesthesia for labor and delivery in high-risk heart disease: General considerations"). Refractory heart failure resulting in need for intubation and ventilation is the only cardiac indication for cesarean delivery and this should be a rare occurrence with state of the art antepartum cardiac care and careful monitoring.

Maternal pulse, oxygen saturation, and blood pressure are generally effectively monitored noninvasively but this practice reflects provider’s practice style. Invasive hemodynamic monitoring such as arterial lines, central venous line, and/or pulmonary artery catheters entail some risk and are rarely necessary in current practice [30]. Invasive hemodynamic monitoring is justified only if the hemodynamic status cannot be reliably assessed noninvasively. (See "Acquired heart disease and pregnancy", section on 'Management of labor and delivery'.)

We administer a single dose of intravenous loop diuretics during the first several hours after delivery to patients with moderate or severe (clinically significant) MS to reduce the likelihood of redistribution edema from autotransfusion following birth [22].

Endocarditis prophylaxis — Endocarditis prophylaxis is not routinely recommended for uncomplicated vaginal or cesarean delivery. In patients with the highest risk lesions (eg, patients with prosthetic heart valves) with established infection that could cause bacteremia (such as chorioamnionitis or pyelonephritis) the underlying infection should be treated in the usual fashion; treatment should include an intravenous regimen effective for infective endocarditis prophylaxis. (See "Pregnancy and valve disease", section on 'Endocarditis prophylaxis' and "Clinical chorioamnionitis" and "Urinary tract infections and asymptomatic bacteriuria in pregnancy", section on 'Acute pyelonephritis'.)

Postpartum — Those who are high risk should be monitored in a special care unit after delivery, such as an intensive care, coronary care, or recovery room setting, where cardiac complications can be monitored and promptly treated. For patients who are admitted to a special care unit, they should be monitored for 24 hours, as post-delivery fluid shifts may be delayed in the presence of regional anesthesia. For those women who required ongoing anticoagulation, anticoagulation can be resumed once there is no evidence of early or late postpartum hemorrhage.

While there are no specific guidelines on the timing of postpartum assessments, cardiac assessment at four to six weeks postpartum will provide an opportunity to screen for postpartum deterioration, adjust cardiac medications, and discuss contraception choices.

Most cardiac medications are excreted in breast milk but in such small amounts that their use in lactating women is generally safe [19]. An exception is amiodarone, which affects the newborn thyroid, so breastfeeding is contraindicated during maternal use of amiodarone.

Contraception can be restarted based on guidelines extrapolated from non-heart disease population. Current recommendations state that combination hormonal contraception should be avoided in women with valvular heart disease associated with high risk during pregnancy, which likely applies to most, if not all, women with MS. Alternatives that are viewed as reasonable (benefit outweighs risk) include intrauterine device, implant, depot medroxyprogesterone acetate, and progestin-only pill [31]. (See "Contraception: Postpartum counseling and methods".)

As the cardiovascular changes of pregnancy do not fully resolve until the sixth postpartum month, a repeat clinical assessment with echocardiography after the sixth postpartum month will serve as the baseline for future follow-up, including risk stratification for future pregnancies. Elective cardiovascular invasive procedures should be delayed until after the sixth postpartum month to avoid unnecessary thromboembolic risk.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac valve disease" and "Society guideline links: Management of cardiovascular diseases during pregnancy".)

SUMMARY AND RECOMMENDATIONS

●With proper counseling and monitoring, most women with mitral stenosis (MS) should have a successful pregnancy. (See 'Nature and frequency of adverse pregnancy outcomes' above and 'Clinical management' above.)

●Clinical assessment prior to pregnancy enables identification of those at high risk (moderate to severe MS, history of cardiac complications prior to pregnancy, poor functional class, pulmonary hypertension). There is an incremental increase in the frequency of maternal and fetal complications with increasing severity of MS (table 1). (See 'Risk stratification' above.)

●Symptomatic patients with moderate to severe MS (mitral valve area ≤1.5 cm²) should undergo intervention, preferably percutaneous balloon mitral valvotomy, before pregnancy. (See 'Indications for preconception intervention' above.)

●The preconception management of asymptomatic women with moderate to severe MS is more controversial and requires consideration of patient and institution specific factors. (See 'Indications for preconception intervention' above.)

●Most common maternal cardiac complications during pregnancy are pulmonary edema and arrhythmias. (See 'Nature and frequency of adverse pregnancy outcomes' above.)

●Prompt anticoagulation and rhythm control are the cornerstones of treatment of atrial tachyarrhythmias in the pregnant women with MS. (See 'Antepartum' above.)

●With appropriate care including judicious use of beta blockers and/or diuretics, most women with MS can undergo pregnancy without the need for invasive interventions. Intervention during pregnancy (preferably by percutaneous mitral balloon valvotomy) is reserved for those patients with severe symptoms despite maximal medical therapy and admission to hospital. (See 'Antepartum' above.)

●Vaginal delivery with assisted second stage is the preferred mode of delivery with caesarian delivery generally reserved for obstetric reasons. (See 'Peripartum' above.)