Metabolic syndrome in obesity: treatment success and adverse pregnancy outcomes with ovulation induction in polycystic ovary syndrome

Abstract

Background: Obesity is common in women with polycystic ovary syndrome. polycystic ovary syndrome and obesity are associated with reduced fertility. The effect of metabolic syndrome on the success of infertility treatment and pregnancy outcomes in women with polycystic ovary syndrome undergoing ovulation induction has not been investigated.

Objective: The objectives of this study were to determine the associations of metabolic syndrome on the rate of live birth after ovulation induction and pregnancy complications in obese women with polycystic ovary syndrome and determine whether there is a difference in outcomes concerning specific medications used for ovulation induction.

Study design: This prospective cohort analysis used data collected from participants in the Pregnancy in Polycystic Ovary Syndrome II clinical trial conducted by the Reproductive Medicine Network. In the Pregnancy in Polycystic Ovary Syndrome II trial, 750 women with polycystic ovary syndrome and infertility were randomized to either clomiphene citrate or letrozole for ovulation induction for 1 to 5 cycles or until pregnancy occurred. Cox regression and modified Poisson regression, chi-square test, and Student t test or Wilcoxon test were used in this study. Outcomes of interest were rates of live birth and clinical pregnancy and pregnancy complications. Having metabolic syndrome was defined by the presence of at least 3 of 5 cardiometabolic risk factors (waist circumference of >88 cm, low high-density lipoprotein cholesterol of <50 mg/dL, triglycerides of ≥150 mg/dL, systolic blood pressure of ≥130 or diastolic blood pressure of ≥85 mm Hg, and fasting glucose of >100 mg/dL). In addition, we used a continuous metabolic syndrome z score. Body mass index categories were defined as normal (body mass index of <25 kg/m²), high (25 to 35 kg/m²), and very high (>35 kg/m²).

Results: As illustrated in the Table, early pregnancy losses showed no difference by metabolic syndrome. Fewer women achieved a clinical pregnancy (20.5% vs 29.7%; P=.007) or had a live birth (16.5% vs 27%; P=.001) in the presence of metabolic syndrome. Early pregnancy losses showed no difference by metabolic syndrome status. However, at least 1 pregnancy complication occurred more often with metabolic syndrome: 61.9% (26 of 42 cases) with metabolic syndrome vs 44.4% (59 of 133 cases) (P=.05) without metabolic syndrome. Gestational diabetes mellitus (35.7% vs 18.2%; P=.02) and macrosomia (21.4% vs 8.3%; P=.02) were more common in the presence of metabolic syndrome. After adjustment for other potential confounders, the rate ratio for live births for a 1-unit change in the metabolic syndrome z score was 0.89 (95% confidence interval, 0.79-1.00; P=.04) for those whose body mass index was 25 to 35 kg/m². For the very high body mass index subgroup (>35 kg/m²), the independent effects of metabolic syndrome from obesity were harder to discern. The rate of live birth was higher with the use of letrozole, although metabolic syndrome had a different detrimental effect concerning the medication given. The overall incidence of pregnancy complications was high (approximately 49%) in the Pregnancy in Polycystic Ovary Syndrome II trial and the 2 medications. Letrozole was associated with more obstetrical complications in the presence of metabolic syndrome, and clomiphene was associated with a lower rate of live birth rate when metabolic syndrome was present.

Conclusion: Metabolic syndrome is a risk factor that lowers the rate of live birth after ovulation for women with polycystic ovary syndrome, independent of obesity, and it is particularly associated with a lower rate of live birth for women using clomiphene compared with women using letrozole. In addition, metabolic syndrome is a risk factor for pregnancy complications for women with obesity using letrozole. Furthermore, having metabolic syndrome is a risk factor for gestational diabetes mellitus and macrosomia.

Keywords: metabolic syndrome; ovulation induction; polycystic ovary syndrome; pregnancy complications.