. Author manuscript; available in PMC: 2015 Jul 1.

Published in final edited form as: J Perinatol. 2014 Aug 7;35(1):23–28. doi: 10.1038/jp.2014.139

Table 3.

Maternal serum 25(OH)D at and risk of operative delivery in 2798 singleton pregnancies.

25(OH)D^a	Cases	% with outcome	Unadjusted risk ratio	95% CI	Adjusted^b risk ratio	95% CI
Primary cesarean delivery	52	1.9
<30 nmol/L	13	1.9	Reference		Reference
30–49 nmol/L	14	1.5	0.78	0.37 – 1.64	0.76	0.38 – 1.55
50–74 nmol/L	19	2.5	1.28	0.64 – 2.57	1.22	0.61 – 2.44
≥75 nmol/L	6	1.4	0.70	0.27 – 1.84	0.65	0.24 – 1.81
Indicated instrumental delivery^c, ^d	211	7.6
<30 nmol/L	50	7.6	Reference		Reference
30–49 nmol/L	63	6.9	0.91	0.63 – 1.31	0.84	0.57 – 1.22
50–74 nmol/L	61	8.1	1.07	0.74 – 1.54	0.92	0.63 – 1.35
≥75 nmol/L	36	8.4	1.10	0.72 – 1.68	0.88	0.56 – 1.39
Primary cesarean or indicated instrumental delivery ^c	262	9.4
<30 nmol/L	63	9.5	Reference		Reference
30–49 nmol/L	77	8.3	0.88	0.64 – 1.22	0.83	0.60 – 1.16
50–74 nmol/L	80	10.5	1.11	0.81 – 1.52	1.00	0.72 – 1.39
≥75 nmol/L	42	9.7	1.02	0.70 – 1.50	0.87	0.58 – 1.30

Note: All data based on combined results from 5 imputed datasets.

Abbreviation: 25(OH)D, 25-hydroxyvitamin D.

25(OH)D measured at ≤26 weeks gestation.

Adjusted for prepregnancy BMI, race/ethnicity, and study site (except cesarean models adjusted for latitude instead of study site). Conditional logistic regression models conditioned on study site and adjusted for prepregnancy BMI and race/ethnicity yielded similar results.

Vaginal delivery by forceps or vacuum excluding those with “elective” listed as indication.

n=2759 women who entered stage 2 labor.