Vitamin D Levels: Is There an Association with Livebirth and/or Miscarriage

BACKGROUND AND PURPOSE:

• Research suggests that serum 25-hydroxyvitamin D (Vitamin D) levels play a role in reproduction
  • Receptors found in important tissues required for normal reproduction
  • Vitamin D may be associated with the immune system
• Data on this topic limited in humans and generally to IVF/fertility centers
• Mumford et al. (The Lancet Diabetes & Endocrinology, 2018) examined the association between preconception vitamin D and livebirth/miscarriage among women without fertility issues

METHODS:

• Secondary analysis of prospective cohort from randomized, double-blind, placebo-controlled trial (RCT)
  • Data from Effects of Aspirin in Gestation and Reproduction (EAGeR) trial
  • Initial trial assessed effects of aspirin on pregnancy loss
• Participants
  • 18-40 years of age
  • 1 or 2 previous pregnancy losses
• Vitamin D was measured at
  • Baseline (preconception)
  • 8 weeks of gestation
• Vitamin D level cut-offs
  • Sufficient concentrations: ≥75 nmol/L
  • Insufficient concentrations: <75 nmol/L
• Primary outcomes
  • Clinical pregnancy
  • Time to pregnancy (Fecundability)
  • Pregnancy loss
  • Livebirths

RESULTS:

• 1,191 women were included in the study with data available on preconception 25- hydroxyvitamin D concentrations
  • 47% sufficient
  • 53% insufficient
• When compared to women with insufficient Vitamin D, women with sufficient preconception Vitamin D were more likely to achieve
  • Clinical pregnancy: adjusted risk ratio (RR) 1.10; 95% CI, 1.01–1.20
  • Livebirth: aRR 1.15; 95% CI, 1.02–1.29
• Among women who achieved pregnancy, sufficient Vitamin D was associated with reduced risk of pregnancy loss at preconception but not at 8 weeks gestation
  • Preconception: RR per 25 nmol/L 0.88; 95% CI, 0.77–0.99
  • 8 weeks: RR per 25 nmol/L 0.98; 95% CI, 0.95–1.01
• There was no association between fecundability with sufficient versus those with insufficient preconception VitD levels

CONCLUSION:

• Sufficient levels of Vitamin D before conception (but not in early pregnancy) are associated with increased likelihood of pregnancy and livebirth
• Vitamin D levels did not affect time to pregnancy, in keeping with previous research

Learn More – Primary Sources:

Association of preconception serum 25-hydroxyvitamin D concentrations with livebirth and pregnancy loss: a prospective cohort study