Vitamin D Reduces Premature Births

So on the new front for Vitamin D supplementation it appears that maintaining high levels of vitamin D greatly reduces the risk for premature births (hat-tip to Sharon Kirkey of the Ottawa Citizen).  Supplementing with 4000 IU of vitamin D per day compared to 400 IU per day reduces the risk of a premature birth by half.  This may have to do with the role of vitamin D in the innate immune system.  Previous research published in the New England Journal of Medicine found that around 25-40 % of pre-term events may have been caused by vaginal infections (Goldenburg et al., 2000). 

This research isn't published in a peer-reviewed journal yet but rather was presented at the Pediatric Academic Societies meeting in Vancouver, May 1-4.  I did, however, manage to track down the abstracts for the conference:

[1665.6] Vitamin D Supplementation during Pregnancy Part 2 NICHD/CTSA Randomized Clinical Trial (RCT): Outcomes

Carol L. Wagner, Donna Johnson, Thomas C. Hulsey, Myla Ebeling, Judy Shary, Pamela G. Smith, Betty Bivens, Bruce W. Hollis. Pediatrics/Obstetrics, Medical University of SC, Charleston, SC.

BACKGROUND: Vitamin D (vitD) deficiency during pregnancy is a serious public health issue, affecting mother and fetus. Establishing optimal vitD requirements of pregnant women is vital in preventing vitD deficiency and its health-associated comorbidities.
OBJECTIVE: Evaluate the effectiveness of high dose vitD supplementation in decreasing pregnancy comorbidity risks.
DESIGN/METHODS: Following their consent, pregnant women 12-16 wks' gestation were randomized into 1 of 3 tx grps stratified by race: 400, 2000 or 4000 IU vitD₃/day until delivery. Women were evaluated for safety (Abstr#750939), efficacy and effectiveness with monthly 25(OH)D; 1,25(OH)₂D; serum Ca, Cr, phos, and urinary Ca/Cr levels, all measured using standardized methodology. Comorbidities of pregnancy (preeclampsia, gest diabetes, any infection, preterm labor (PTL)/preterm birth (PTB) <37 wks GA) were recorded prospectively for each subject. Investigators and health team were blinded to tx grp.
RESULTS: Of the 494 women who enrolled in the study, 350 women continued until delivery: 98 African American (AA), 137 Hispanic (Hisp) and 115 Caucasian (Cauc) women; with 111 controls, 122 in 2000 IU and 117 in 4000 IU groups. There were no differences in baseline vitD status between dose groups. The mean 25(OH)D by dose group at delivery, as chronic level, and 1-month before delivery were significantly different between control and 2000, control and 4000, and 2000 vs. 4000 (p<0.0001). 25(OH)D had a direct influence on 1,25(OH)₂D levels throughout pregnancy (p<0.0001) with 25(OH)D of 40 ng/mL required to obtain maximum 1,25(OH)₂D production. In bivariate analyses controlling for race, PTL/PTB and infection were inversely related to 25(OH)D and were lowest in the 4000 IU grp (p<0.0001). In logistic regression, comparing 400 vs. 4000 IU and controlling for race, the risk of comorbidities were 0.50 (CI 0.27-0.95; p=0.03) among those in the 4000 IU grp. Using least sq means, when adjusting for race, 25(OH)D of women with comorbidities was 33.4 ng/mL compared to 39.0 ng/mL in those women without (p < 0.008).
CONCLUSIONS: VitD sufficiency was strongly associated with decreased risk for PTL/PTB and infection during pregnancy and comorbities of pregnancy, with the greatest effect with 4000 IU vitamin D/day regimen. Therefore, to attain a minimal 25(OH)D level of 40 ng/mL, we recommend 4000 IU/day for all pregnant women.E-PAS20101665.6

Not that infection rates were inversely related to serum vitamin D levels.

Now, there used to be concerns over whether high vitamin D levels could cause birth defects related to calcium metabolism.  The researchers found these claims to be baseless.

Vitamin D Supplementation during Pregnancy Part I NICHD/CTSA Randomized Clinical Trial (RCT): Safety Considerations

Carol L. Wagner, Donna Johnson, Thomas C. Hulsey, Myla Ebeling, Judy Shary, Pamela G. Smith, Betty Bivens, Bruce W. Hollis. Pediatrics, Medical University of SC, Charleston, SC.

BACKGROUND: Vitamin D (vitD) deficiency during pregnancy is a serious public health issue that affects both mother and fetus. Establishing the optimal vitD requirements of the pregnant woman is vital in preventing vitD deficiency.
OBJECTIVE: Evaluate the safety of high dose vitD supplementation during pregnancy in a RCT.
DESIGN/METHODS: Following their consent, pregnant women 12-16 wks' gestation were randomized into 1 of 3 treatment (tx) groups (grps) stratified by race: 400, 2000 or 4000 IU vitD₃/day until delivery. Women were evaluated for safety, efficacy and effectiveness with monthly 25(OH)D; 1,25(OH)₂D; serum Ca, Cr, phos, and urinary Ca/Cr levels, all measured using standardized methodology. Investigators & health team were blinded to tx grp.
RESULTS: Of the 494 women who enrolled in the study, 350 women continued until delivery: 98 African American, 137 Hispanic and 115 Caucasian women; with 111 controls, 122 in 2000 IU and 117 in 4000 IU grps. There were no differences in baseline 25(OH)D by dose grp. The mean 25(OH)D by dose grp at delivery, as chronic level, and 1-month before delivery were significantly different between control and 2000, control and 4000, and 2000 vs. 4000 (p<0.0001). 25(OH)D had a direct influence on 1,25(OH)₂D levels throughout pregnancy (p<0.0001). Throughout the study, there were no differences between grps on any safety measure: serum Ca, Cr, urinary Ca/Cr ratios (pNS between grps). Not a single adverse event was attributed to vitD supplementation by the DSMB. Neonatal 25(OH)D was significantly correlated with maternal 25(OH)D overall, 1-month prior and at delivery (r²=0.6; OR 0.50); and was significantly different by tx group: 18.2±10.1 (control), 22.8±9.8 (2000 IU) and 26.5±10.3 ng/mL (4000 IU), (p<0.0001).

An interesting pair of abstracts to be sure.  I look forward to seeing the data for myself when it's published.