Prenatal vitamin C and E supplementation in smokers is associated with reduced placental abruption and preterm birth: a secondary analysis

• Published in: BJOG : an international journal of obstetrics and gynaecology Vol. 122; no. 13; pp. 1740 - 1747
• Main Authors: Abramovici, A, Gandley, RE, Clifton, RG, Leveno, KJ, Myatt, L, Wapner, RJ, Thorp, JM, Mercer, BM, Peaceman, AM, Samuels, P, Sciscione, A, Harper, M, Saade, G, Sorokin, Y
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-12-2015
• Subjects: Abruptio Placentae - epidemiology; Adolescent; Adult; Ascorbic Acid - administration & dosage; Dietary Supplements; Double-Blind Method; Female; Humans; Hypertension, Pregnancy-Induced - epidemiology; Placental abruption; Pre-Eclampsia - epidemiology; Preeclampsia; Pregnancy; Premature birth; Premature Birth - epidemiology; preterm birth; Smoking; Smoking - epidemiology; Vitamin C; Vitamin E; Vitamin E - administration & dosage; Vitamins - administration & dosage; Young Adult; preterm birth; Placental abruption; smoking
• ISSN: 1470-0328; 1471-0528
• DOI: 10.1111/1471-0528.13201

Objective
Smoking and pre‐eclampsia (PE) are associated with increases in preterm birth, placental abruption and low birthweight. We evaluated the relationship between prenatal vitamin C and E (C/E) supplementation and perinatal outcomes by maternal self‐reported smoking status focusing on outcomes known to be impacted by maternal smoking.
Design/Setting/Population
A secondary analysis of a multi‐centre trial of vitamin C/E supplementation starting at 9–16 weeks in low‐risk nulliparous women with singleton gestations.
Methods
We examined the effect of vitamin C/E by smoking status at randomisation using the Breslow–Day test for interaction.
Main outcome measures
The trial's primary outcomes were PE and a composite outcome of pregnancy‐associated hypertension (PAH) with serious adverse outcomes. Perinatal outcomes included preterm birth and abruption.
Results
There were no differences in baseline characteristics within subgroups (smokers versus nonsmokers) by vitamin supplementation status. The effect of prenatal vitamin C/E on the risk of PE (P = 0.66) or PAH composite outcome (P = 0.86) did not differ by smoking status. Vitamin C/E was protective for placental abruption in smokers (relative risk [RR] 0.09; 95% CI 0.00–0.87], but not in nonsmokers (RR 0.92; 95% CI 0.52–1.62) (P = 0.01), and for preterm birth in smokers (RR 0.76; 95% CI 0.58–0.99) but not in nonsmokers (RR 1.03; 95% CI 0.90–1.17) (P = 0.046).
Conclusion
In this cohort of women, smoking was not associated with a reduction in PE or the composite outcome of PAH. Vitamin C/E supplementation appears to be associated with a reduction in placental abruption and preterm birth among smokers.