Recent trends, risk factors, and disparities in low birth weight in California, 2005–2014: a retrospective study

Abstract

BackgroundLow birth weight (LBW) is a leading risk factor for infant morbidity and mortality in the United States. There are large disparities in the prevalence of LBW by race and ethnicity, especially between African American and White women. Despite extensive research, the practice of clinical and public health, and policies devoted to reducing the number of LBW infants, the prevalence of LBW has remained unacceptably and consistently high. There have been few detailed studies identifying the factors associated with LBW in California, which is home to a highly diverse population. The aim of this study is to investigate recent trends in the prevalence of LBW infants (measured as a percentage) and to identify risk factors and disparities associated with LBW in California.MethodsA retrospective cohort study included data on 5,267,519 births recorded in the California Birth Statistical Master Files for the period 2005–2014. These data included maternal characteristics, health behaviors, information on health insurance, prenatal care use, and parity. Logistic regression models identified significant risk factors associated with LBW. Using gestational age based on obstetric estimates (OA), small for gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) infants were identified for the periods 2007–2014.ResultsThe number of LBW infants declined, from 37,603 in 2005 to 33,447 in 2014. However, the prevalence of LBW did not change significantly (6.9% in 2005 to 6.7% in 2014). The mean maternal age at first delivery increased from 25.7 years in 2005 to 27.2 years in 2014. The adjusted odds ratio showed that women aged 40 to 54 years were twice as likely to have an LBW infant as women in the 20 to 24 age group. African American women had a persistent 2.4-fold greater prevalence of having an LBW infant compared with white women. Maternal age was a significant risk factor for LBW regardless of maternal race and ethnicity or education level. During the period 2017–2014, 5.4% of the singleton births at 23–41 weeks based on OE of gestational age were SGA infants (preterm SGA + term SGA). While all the preterm SGA infants were LBW, both preterm AGA and term SGA infants had a higher prevalence of LBW.ConclusionsIn California, during the 10 years from 2005 to 2014, there was no significant decline in the prevalence of LBW. However, maternal age was a significant risk factor for LBW regardless of maternal race and ethnicity or education level. Therefore, there may be opportunities to reduce the prevalence of LBW by reducing disparities and improving birth outcomes for women of advanced maternal age.Electronic supplementary materialThe online version of this article (10.1186/s40748-018-0084-2) contains supplementary material, which is available to authorized users.

Maternal and infant predictors of infant mortality in California, 2007–2015

“…The rate of preterm birth and evaluation of SGA and LGA in the US depends on the method used to assign gestational age [11]. However, in 2010, Olsen et al developed and validated new intrauterine growth curves based on a racially diverse US population sample for the identification of SGA and LGA infants [10] and this classification has been employed for a few studies [12,13]. However, there are remaining gaps in understanding the roles of SGA and LGA in predicting infant mortality rates from population studies using large datasets.…”

“…A previously reported methodology was used to identify low birth weight (LBW), preterm birth (PTB), SGA, LGA, and cesarean delivery (CD) from the dataset. These factors were coded as dichotomous variables and indicated whether the infant was LBW, PTB, SGA, AGA, LGA, or CD [12,13].…”

“…Data were analyzed on parity and whether women had prenatal care during the first trimester of pregnancy, which are recognized factors associated with health outcomes for the mother and infant [12,13].…”

Smoking during Pregnancy and Adverse Birth and Maternal Outcomes in California, 2007 to 2016

“…For singleton births at 23 to 41 weeks of gestation, we applied the methodology described by Ratnasiri et al to identify SGA births in the study population. 17 CD was categorized as a dichotomous variable identified from "method of delivery" in the BSMF.…”

Women's Reproductive Rights Policies and Adverse Birth Outcomes: A State-Level Analysis to Assess the Role of Race and Nativity Status

“…34 From 2007 to 2016, the prevalence of PTB increased by 2% among foreign-born women and declined by 11.5% among U.S.-born women, 35 with similar trends for LBW. 36 Studies have attempted to disentangle the causes of disparities in adverse birth outcomes, with most focusing on individual-level factors. 37,38 However, advancements in the field highlight the importance of the historical and social context in explaining these disparities.…”