Vitamin D Deficiency Is Associated With Poor Ovarian Stimulation Outcome in PCOS but Not Unexplained Infertility

Samantha F. Butts; David B. Seifer; Nathanael Koelper; Suneeta Senapati; Mary D. Sammel; Andrew N. Hoofnagle; Andrea Kelly; Steven A. Krawetz; Nanette Santoro; Heping Zhang; Michael P. Diamond; Richard S. Legro for the Eunice Kennedy Shriver National Institute of Child Health and Human Development Reproductive Medicine Network

Disclosures

J Clin Endocrinol Metab. 2019;104(2):369-378. 

In This Article

Results

Vitamin D status was evaluated in serum from a total of 607 PPCOS II subjects (81% of 750 original participants) and 647 AMIGOS subjects (71.9% of 900 original participants). Baseline demographics and clinical features of the study cohorts are summarized in Table 1. In PPCOS II and AMIGOS, 41%and 25%of subjectsmet criteria for vitamin D deficiency, respectively. Poor vitamin D status was significantly more prevalent in PPCOS participants than AMIGOS participants (P < 0.0001).

Demographic Variables and Hormonal and Metabolic Markers as Functions of Vitamin D Status: PPCOS II

Consistent with established risk factors for poor vitamin D status, black race (P < 0.0001) and obesity (P < 0.0001) were associated with higher prevalence of D deficiency in PPCOS II subjects (Table 2). Subjects with D deficiency were significantly more likely than those without D deficiency to have higher degrees of hyperandrogenemia and insulin resistance. Although mean anti-Müllerian hormone (AMH) was comparable across vitamin D groups, a statistically significant positive linear association between AMH and 25(OH)D was observed (Pearson r, 0.2; P < 0.0001).

Ovulation as a Function of Vitamin D Status: PPCOS II

A total of 2262 ovulation induction cycles were carried out among the 595 PPCOS II subjects evaluated. The cumulative ovulation rate of 42.4% (959 ovulatory cycles of a total of 2262 treatment cycles) in subjects with D deficiency was significantly lower than the cumulative ovulation rate of 57.6% (1303 ovulatory cycles of 2262 total treatment cycles) in subjects without D deficiency (P = 0.008). Moreover, 23% of the PPCOS II subjects demonstrated resistance to ovarian stimulation by completing the trial without any evidence of ovulation in response to either Clomid or letrozole. Subjects with D deficiency were 21% less likely to ovulate at all in response to ovarian stimulation than those without D deficiency (P = 0.03, Table 3). After adjusting for the effects of race, obesity, treatment received during PPCOSII (Clomid vs letrozole), baseline AMH, LH, testosterone, and degree of insulin resistance, D deficiency remained a significant predictor of resistance to ovulation induction [adjusted OR (AOR), 0.82, 95%CI, 0.68 to 0.99; P=0.04; Table 3].

Pregnancy as a Function of Vitamin D Status: PPCOS II

A total of 205 PPCOS II subjects (33.8% of the PPCOS II subjects evaluated) achieved a pregnancy with ovarian stimulation. PPCOS II subjects with D deficiency had a 28% positive pregnancy rate, whereas those who were not vitamin D deficient had a 37.8% positive pregnancy rate (P = 0.01, Table 4). Subjects who were vitamin D deficient were significantly less likely to achieve a pregnancy than those who were not deficient after controlling for the effects of age, study treatment (Clomid vs letrozole), and obesity (AOR, 0.69; 95% CI, 0.48 to 0.99; P = 0.049). Of the subjects ultimately achieving a live birth, median time from randomization to initial positive pregnancy test was 22 days longer in those with D deficiency than in those who were not deficient (P = 0.03). This difference is depicted graphically in Figure 1.

Figure 1.

Time from PPCOS II randomization to pregnancy (d) according to vitamin D status.

Early Pregnancy Loss as a Function of Vitamin D Status: PPCOS II

Of the PPCOS II subjects evaluated who achieved a pregnancy, 45 (22%) experienced a subsequent pregnancy loss by gestation week 12. Although pregnancy loss was more likely to occur in subjects with Ddeficiency (26%) than in those who were non-D deficient (18%), this association did not achieve statistical significance (Table 4, P = 0.3).

Live Birth as a Function of Vitamin D Status: PPCOS II

Of the PPCOS II subjects evaluated, 25.7% (n = 156) achieved a live birth. The live birth rate in subjects who were D-deficient was 19% compared with 30% in in those without vitamin D deficiency (P = 0.02). Independent of the effects of age, race, obesity, study treatment, degree of insulin resistance, and quartiles of total testosterone, women with D deficiency were 37% less likely to achieve a live birth than those were not vitamin D deficient (AOR, 0.63; 95% CI, 0.41 to 0.98; P = 0.04; Table 5). Season of the blood draw that generated subject samples for 25(OH)D assessment was not included in the final live birth model because adjusting for season resulted in minimal change to the point estimate for vitamin D deficiency (AOR, 0.61; 95% CI, 0.39 to 0.95; P = 0.03) and the season variables did not have a substantial association with live birth in the model. The correlation between the coefficients for BMI and vitamin D deficiency in the live birth model was assess to the degree of collinearity between these variables as a potential challenge to the validity of our findings. The weak correlation (−0.145) between the vitamin D deficiency and BMI coefficients indicates that these variables were not collinear in our live birth model and supports the stability of our estimates.

There was no important interaction between D deficiency and treatment arm or between D deficiency and race on the odds of live birth.

Reproductive Outcomes as a Function of Vitamin D Status: AMIGOS

A total of 228 AMIGOS subjects (34.7%) achieved a positive pregnancy with study treatment. Pregnancy rates were comparable in subjects with and without D deficiency (35.9% and 34.2%, respectively; OR 1.07 95% CI 0.73–1.58, P = 0.7). Of the pregnancies achieved by AMIGOS participants (n = 228), nearly 21% were complicated by a subsequent early pregnancy loss (n = 47). Subjects with D deficiency experienced an early pregnancy loss rate of 28.3% which was 80% higher (OR 1.82, 95% CI 0.92–3.61, P = 0.09) than in thosewhowere not deficient (18%). The cumulative live birth rate in AMIGOS subjects evaluated was 30% (n = 194). In subjects with D deficiency the live birth rate was 32% compared with 29% in those who were not vitamin D deficient (OR 1.1, 95% CI 0.7–1.7, P = 0.5).

Early Pregnancy Loss as a Function of Vitamin D Status—AMIGOS and PPCOS II Combined

When combining subjects from both RMN studies to evaluate the association between preconception vitamin D status and subsequent early pregnancy loss, a total of 92 early losses were observed (21.3%). Subjects with D deficiency were 60%more likely to experience a pregnancy loss than were subjects without vitamin D deficiency (pregnancy loss rate 27.1% and 18.8%, respectively; OR, 1.6; 95% CI, 1.0 to 2.6; P = 0.05).

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