Vitamin D Deficiency Linked to Greater Risk for Primary Cesarean Delivery

1. According to the study by Merewood and colleagues, which of the following statements about the association between vitamin D status and the risk for cesarean delivery is not correct?


A. The rate of cesarean delivery was 14% in women with 25(OH)D levels of 37.5 nmol/L or more vs 28% in women with serum 25(OH)D levels less than 37.5 nmol/L
.
B. Compared with women in whom 25(OH)D levels were 37.5 nmol/L or more, those with 25(OH)D levels less than 37.5 nmol/L had a nearly 4-fold higher risk for cesarean delivery, after controlling for other factors
.
C. Women who had cesarean deliveries had a lower median 25(OH)D level vs women who had a vaginal delivery
.
D. This study proves that vitamin D supplementation during pregnancy can significantly reduce the rate of cesarean delivery

2. According to the study by Merewood and colleagues, which of the following is a risk factor for cesarean delivery?


A. Black and/or Hispanic
B. Born outside of the United States
C. Abstinence from alcohol during pregnancy
D. 25(OH)D levels less than 37.5 nmol/L


Answer / Explanation:


According to the study by Merewood and colleagues, which of the following statements about the association between vitamin D status and the risk for cesarean delivery is not correct?

[HIDE]Answer: This study proves that vitamin D supplementation during pregnancy can significantly reduce the rate of cesarean delivery

This was an observational study; a randomized clinical trial is needed to determine if adequate vitamin D supplementation during pregnancy could decrease the rate of cesarean delivery.

[/HIDE]

According to the study by Merewood and colleagues, which of the following is a risk factor for cesarean delivery?

[HIDE]Answer: 25(OH)D levels less than 37.5 nmol/L

Compared with women who had a vaginal delivery, those who had a cesarean delivery were significantly more likely to be white or non-Hispanic vs black and/or Hispanic, to be born in the United States, and to have used alcohol in pregnancy.

[/HIDE]
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Reference:



Vitamin D Deficiency Linked to Greater Risk for Primary Cesarean Delivery


December 23, 2008 — Vitamin D deficiency in pregnancy is associated with increased odds of primary cesarean delivery, according to the results of a study reported in the December 23 Online First issue of the Journal of Clinical Endocrinology & Metabolism.

"At the turn of the 20th century, women commonly died in childbirth due to 'rachitic pelvis,' " write Anne Merewood, MPH, IBCLC, from Boston University School of Medicine in Massachusetts, and colleagues. "Although rickets virtually disappeared with the discovery of the hormone 'vitamin' D, recent reports suggest vitamin D deficiency is widespread in industrialized nations. Poor muscular performance is an established symptom of vitamin D deficiency, [and] the current US caesarean birth rate is at an all-time high of 30.2%."

The objective of this study was to determine the relationship between maternal serum 25-hydroxyvitamin D [25(OH)D] levels and the rate of primary cesarean delivery.

At an urban teaching hospital in Boston, with 2500 births per year, the investigators measured maternal and infant serum 25(OH)D at birth in 253 mother-infant pairs, of whom 43 (17%) had a primary cesarean delivery. Demographic and medical data were abstracted from the maternal medical record.

The rate of cesarean delivery was 14% in women with 25(OH)D levels of 37.5 nmol/L or higher and 28% in women with serum 25(OH)D levels less than 37.5 nmol/L (P = .012). The risk for cesarean delivery was nearly 4-fold higher in women with 25(OH)D levels less than 37.5 nmol/L vs those with 25(OH)D levels of 37.5 nmol/L or more, based on multivariable logistic regression analysis controlling for race, age, educational level, insurance status, and alcohol use (adjusted odds ratio [OR], 3.84; 95% confidence interval [CI], 1.71 - 8.62).

Limitations of this study include sample too small to determine whether vitamin D deficiency is related to specific types of cesarean deliveries, such as cephalopelvic disproportion or failure to progress.

"Vitamin D deficiency was associated with increased odds of primary caesarean section," the study authors write. "A randomized clinical trial is now needed to determine if adequate vitamin D supplementation during pregnancy to raise blood levels above 37.5 nmol/L can reduce the caesarean section rate."


Study Highlights

•The goal of the study was to evaluate the association between maternal serum 25(OH)D levels and the rate of primary cesarean delivery.
•Women were enrolled between March 21, 2005, and March 20, 2007, on the postpartum unit at Boston Medical Center, an urban teaching hospital in Boston, Massachusetts, within 72 hours of giving birth.
•Demographic and medical data were abstracted from the maternal medical record.
•Women having a repeated cesarean delivery were excluded from this analysis.
•Other exclusion criteria included absence from Boston for more than 2 months during pregnancy; race or ethnicity not black, white, or Hispanic (because of low numbers available in other groups); admission of the infant to intensive care; prematurity; and maternal history of parathyroid, renal, or liver disease, or illegal drug use.
•Enrollment was evenly distributed with time to ensure that data were collected in all seasons, as vitamin D status fluctuates with seasonal sunlight exposure.
•Maternal and infant serum 25(OH)D levels at birth were measured in 253 mother-infant pairs.
•Primary cesarean delivery was performed in 43 women (17%).
•Rate of cesarean delivery was 14% in women with 25(OH)D levels of 37.5 nmol/L or higher vs 28% in women with serum 25(OH)D levels lower than 37.5 nmol/L (P = .012).
•Compared with women in whom 25(OH)D levels were 37.5 nmol/L or higher, those with 25(OH)D levels less than 37.5 nmol/L had a nearly 4-fold higher risk for cesarean delivery, based on multivariable logistic regression analysis controlling for race, age, educational level, insurance status, and alcohol use (adjusted OR, 3.84; 95% CI, 1.71 - 8.62).
•Women who had cesarean delivery had a lower median 25(OH)D level vs women who had a vaginal delivery (45.0 nmol/L vs 62.5 nmol/L; P = .007).
•The investigators concluded that vitamin D deficiency was associated with increased odds of primary cesarean delivery and that a randomized clinical trial was needed to determine if adequate vitamin D supplementation during pregnancy to raise blood levels above 37.5 nmol/L could decrease the rate of cesarean deliveries.
•Compared with women who had a vaginal delivery, those who had a cesarean delivery were also significantly more likely to be white or non-Hispanic vs black and/or Hispanic (OR, 3.81; 95% CI, 1.47 - 9.86; P = .006), to be born in the United States (OR, 2.14; 95% CI, 1.10 - 4.16; P = .023), and to have used alcohol in pregnancy (OR, 2.92; 95% CI, 1.02 - 8.38; P = .039).
•Limitations of the study include low participation rate and sample too small to determine whether vitamin D deficiency is related to specific types of cesarean deliveries, such as cephalopelvic disproportion or failure to progress.


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