Can Polycystic Ovary Syndrome (PCOS) in a pregnant woman affect the fetus?

Can PCOS in Pregnant Women Affect the Fetus?

Yes, PCOS significantly increases the risk of adverse fetal outcomes, including preterm birth, small-for-gestational-age infants, large-for-gestational-age infants, and neonatal intensive care unit admissions, with these risks being independent of obesity in some complications. 1, 2

Fetal and Neonatal Complications

PCOS creates a high-risk pregnancy environment that directly impacts fetal development and neonatal health through multiple mechanisms:

Direct Fetal Growth Abnormalities

• Both growth restriction and excessive growth occur: PCOS is associated with both small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants, likely due to impaired insulin-mediated growth and fetal programming 1, 2
• The mechanism involves maternal hyperinsulinemia and hyperandrogenism affecting placental function and fetal nutrient delivery 3

Preterm Birth Risk

• Preterm delivery rates are significantly elevated in PCOS pregnancies, contributing to increased neonatal morbidity 2
• This risk persists even when controlling for other factors like obesity 1

Neonatal Intensive Care Requirements

• NICU admission rates are increased in infants born to mothers with PCOS, reflecting the cumulative impact of prematurity, growth abnormalities, and metabolic complications 2

Maternal Complications That Secondarily Affect the Fetus

Gestational Diabetes Mellitus

• GDM incidence is significantly higher in PCOS pregnancies, even in lean women with PCOS compared to lean controls 4
• This metabolic complication directly impacts fetal growth patterns and increases risk of macrosomia 1, 5

Hypertensive Disorders

• Pregnancy-induced hypertension and preeclampsia rates are elevated, though the data for this association is weaker than for GDM 1, 4
• These conditions compromise placental perfusion and fetal oxygenation 2

Early Pregnancy Loss

• First-trimester miscarriage rates are increased, attributed to obesity, hyperinsulinemia, elevated luteinizing hormone, and endometrial dysfunction 1

Risk Stratification and Obesity

A critical distinction: While obesity worsens outcomes, PCOS itself confers independent risk:

• When lean PCOS women are compared to lean controls, the increased incidence of GDM and pregnancy-induced hypertension remains statistically significant 4
• However, when obese PCOS women are compared to obese controls, pregnancy complication rates become similar, suggesting obesity is a major modifiable risk factor 4
• The Amsterdam Consensus Guidelines confirm that obesity and insulin resistance worsen both maternal and fetal complications 2

Recommended Management Approach

Preconception Optimization

• Screen for metabolic abnormalities before conception: fasting glucose, 2-hour glucose tolerance test, and lipid profile 6
• Target 5-10% weight loss in overweight/obese women, as this significantly improves both metabolic and reproductive outcomes 6
• Consider metformin for women with documented insulin resistance to improve ovulation and reduce metabolic risk 6, 5

During Pregnancy Monitoring

• Perform early glucose screening using 75-g oral glucose tolerance test at preconception or within the first 20 weeks, then repeat at 24-28 weeks 5
• Monitor blood pressure, kidney function, and proteinuria regularly throughout pregnancy 7
• Administer low-dose aspirin from week 12 to week 36 to reduce preeclampsia risk 6
• Closer surveillance is mandatory, especially in obese women with PCOS 2

Postpartum Considerations

• Recognize that PCOS increases long-term maternal risk for type 2 diabetes, cardiovascular events, and endometrial cancer 3
• Breastfeeding should be encouraged, as longer lactation duration is associated with reduced maternal metabolic complications 8

Clinical Pitfalls to Avoid

• Do not assume normal glucose tolerance: Even lean women with PCOS require early and repeated glucose screening 4
• Do not attribute all risk to obesity alone: PCOS confers independent metabolic and reproductive risks 1, 4
• Do not delay preconception counseling: Risk modification through lifestyle changes and metabolic optimization must begin before conception 6, 5
• Do not use standard screening timelines: Women with PCOS require earlier and more frequent metabolic screening than the general obstetric population 5