|Title||Women's prepregnancy underweight as a risk factor for preterm birth: a retrospective study.|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Girsen AI, Mayo JA, Carmichael SL, Phibbs CS, Shachar BZ, Stevenson DK, Lyell DJ, Shaw GM, Gould JB|
|Corporate Authors||March of Dimes Prematurity Research Center at Stanford University School of Medicine|
|Date Published||2016 Nov|
|Keywords||Adult, Body Mass Index, California, Female, Gestational Age, Humans, Infant, Newborn, Parity, Pregnancy, Premature Birth, Retrospective Studies, Risk Factors, Severity of Illness Index, Thinness|
OBJECTIVE: To investigate the distribution of known factors for preterm birth (PTB) by severity of maternal underweight; to investigate the risk-adjusted relation between severity of underweight and PTB, and to assess whether the relation differed by gestational age.
DESIGN: Retrospective cohort study.
SETTING: State of California, USA.
METHODS: Maternally linked hospital and birth certificate records of 950 356 California deliveries in 2007-2010 were analysed. Singleton live births of women whose prepregnancy body mass index (BMI) was underweight (<18.5 kg/m ) or normal (18.50-24.99 kg/m ) were analysed. Underweight BMI was further categorised as: severe (<16.00), moderate (16.00-16.99) or mild (17.00-18.49). PTB was grouped as 22-27, 28-31, 32-36 or <37 weeks (compared with 37-41 weeks). Adjusted multivariable Poisson regression modeling was used to estimate relative risk for PTB.
MAIN OUTCOME MEASURES: Risk of PTB.
RESULTS: About 72 686 (7.6%) women were underweight. Increasing severity of underweight was associated with increasing percent PTB: 7.8% (n = 4421) in mild, 9.0% (n = 1001) in moderate and 10.2% (475) in severe underweight. The adjusted relative risk of PTB also significantly increased: adjusted relative risk (aRR) = 1.22 (95% CI 1.19-1.26) in mild, aRR = 1.41 (95% CI 1.32-1.50) in moderate and aRR = 1.61 (95% CI 1.47-1.76) in severe underweight. These findings were similar in spontaneous PTB, medically indicated PTB, and the gestational age groupings.
CONCLUSION: Increasing severity of maternal prepregnancy underweight BMI was associated with increasing risk-adjusted PTB at <37 weeks. This increasing risk was of similar magnitude in spontaneous and medically indicated births and in preterm delivery at 28-31 and at 32-36 weeks of gestation.
TWEETABLE ABSTRACT: Increasing severity of maternal underweight BMI was associated with increasing risk of preterm birth.
|PubMed Central ID||PMC5069076|
|Grant List||UL1 TR001085 / TR / NCATS NIH HHS / United States|