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Clin Infect Dis. 2016 Aug 15;63(4):487-94. doi: 10.1093/cid/ciw290. Epub 2016 May 3.

The Effect of Influenza Vaccination on Birth Outcomes in a Cohort of Pregnant Women in Lao PDR, 2014-2015.

Author information

1
Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia.
2
Ministry of Health.
3
Influenza Program, U.S. CDC-Lao People's Democratic Republic, American Embassy.
4
Mother and Child Hospital.
5
Setthathirath Hospital, Vientiane.
6
Luang Prabang Provincial Hospital, Lao People's Democratic Republic.
7
Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia.
8
Influenza Program, U.S. CDC-Lao People's Democratic Republic, American Embassy The QED Group, American Embassy, Vientiane, Lao People's Democratic Republic.

Erratum in

Abstract

BACKGROUND:

Some studies suggest that maternal influenza vaccination can improve birth outcomes. However, there are limited data from tropical settings, particularly Southeast Asia. We conducted an observational study in Laos to assess the effect of influenza vaccination in pregnant women on birth outcomes.

METHODS:

We consented and enrolled a cohort of pregnant woman who delivered babies at 3 hospitals during April 2014-February 2015. We collected demographic and clinical information on mother and child. Influenza vaccination status was ascertained by vaccine card. Primary outcomes were the proportion of live births born small for gestational age (SGA) or preterm and mean birth weight. Multivariate models controlled for differences between vaccinated and unvaccinated women and influenza virus circulation.

RESULTS:

We enrolled 5103 women (2172 [43%] were vaccinated). Among the 4854 who had a live birth, vaccinated women were statistically significantly less likely than unvaccinated women to have an infant born preterm during the period of high influenza virus circulation (risk ratio [RR] = 0.56, 95% confidence interval [CI], .45-.70), and the effect remained after adjusting for covariates (adjusted RR, 0.69; 95% CI, .55-.87). There was no effect of vaccine on mean birth weight. Vaccinated mothers had a statistically significant elevated risk of having an infant born SGA (adjusted RR, 1.25; 95% CI, 1.11–1.41).

CONCLUSIONS:

In this observational study, we found indirect evidence of influenza vaccine safety during pregnancy, and women who received vaccine had a reduced risk of delivering a preterm infant during times of high influenza virus circulation. Vaccination may prevent 1 in 5 preterm births that occur during periods of high influenza circulation.

KEYWORDS:

Laos; influenza vaccine; pregnant woman; preterm birth; small for gestational age

PMID:
27143672
PMCID:
PMC4970914
DOI:
10.1093/cid/ciw290
[Indexed for MEDLINE]
Free PMC Article

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