Newborn health, measured by birth weight, is an important marker that not only reflects an infant's immediate well-being but is also a strong predictor of future health and development, including neonatal mortality, stunting, neurological and cognitive development, and diseases in adulthood [1]. Low birth weight (LBW), defined as infants born weighing less than 2,500 grams (5.5 pounds) according to the World Health Organization [2], remains a global public health concern with far-reaching consequences in low- and middle-income countries (LMICs). Of the 130 million infants born every year, approximately 20 million are born as LBW infants, amounting to an annual LBW prevalence of 15% globally [2]. Marete et al. (2020) reported that the global incidence of LBW differs by region, with the highest rates observed in South Asia at 28%, followed by 13% in sub-Saharan Africa, 9% in Latin America, and 6% in East Asia and the Pacific [3]. Among sub-Saharan African countries, Gambia exhibits some of the highest LBW rates, at 7.2% [4].
Intrauterine growth restriction (IUGR), which is often a comorbidity of preterm birth, can lead to premature delivery, both assisted and non-assisted, and is a common cause of LBW [5, 6]. A recent systematic review and meta-analysis of the effect of antenatal care (ANC) on LBW in Africa found that at least one ANC visit had a statistically significant effect on birth weight [7]. This finding is consistent with recent studies that have shown that adequate ANC attendance is crucial for reducing LBW risks [8, 9]. The WHO initially recommended at least four ANC visits during pregnancy, but this was revised in 2016 to suggest a minimum of eight visits [10]. Evidence indicates that missing these recommended ANC visits significantly increases the risk of LBW [10], a view supported by the role of ANC in delivering various therapies that improve maternal and fetal health outcomes [11]. Furthermore, LBW has been linked to missing five to eight ANC appointments, the absence of ANC in the first trimester, and a lack of essential ANC supplies [8, 12]. While there is some debate over the specific impact of ANC interventions on maternal and neonatal health [13, 14], research indicates that although ANC alone may not enhance birth outcomes, integrating it with other healthcare programs can significantly reduce perinatal and neonatal mortality [15, 16].
Numerous studies have underscored how ANC visits are crucial for improving neonatal health outcomes in LMICs, especially for reducing the incidence of LBW. According to a systematic review by Conde-Agudelo et al. (2012), regular ANC visits are significantly associated with a reduction in LBW rates, as these appointments allow timely interventions and health guidance tailored to mothers’ needs [17]. Furthermore, Wastnedge et al. (2021) highlighted that in LMICs, tailored ANC programs that include frequent and comprehensive visits can effectively decrease the rate of preterm birth [18]. These visits allow healthcare providers to manage maternal conditions such as hypertension and diabetes, which are prevalent in LMICs and linked to adverse birth outcomes. ANC also facilitates nutritional counseling and supplementation and educates expecting mothers about risk factors leading to neonatal complications. This comprehensive care model not only addresses immediate health concerns but also sets a foundation for long-term neonatal health, underscoring the critical role of consistent and quality ANC in resource-limited settings [19].
Low birth weight (LBW) birth weight in the Gambia remains a significant challenge, with various studies highlighting the crucial role of ANC in improving birth outcomes. A prospective cohort study among women who attended an urban health center in Gambia found that regular ANC visits were linked to improved outcomes. Women who had four or more ANC visits during pregnancy were less likely to deliver a baby with LBW than those who attended fewer visits [20]. Further evidence from Gambia underscores the positive impact of comprehensive, early ANC visits on reducing the incidence of preterm births and subsequent LBW rates within the Gambia [21].
While these studies show an association between ANC visits and birth outcomes, there is limited empirical evidence estimating the causal effects of ANC visits on LBW infants. Choice variables such as ANC visits are frequently influenced by maternal and household characteristics, leading to systematic differences in the characteristics of mothers who have an adequate number of ANC visits compared to mothers with fewer than adequate ANC visits [22]. Consequently, it is essential to consider and adjust for these systematic variations when estimating the impact of treatment on outcomes. Propensity score matching (PSM) is a quasi-experimental method used to estimate the difference in outcomes between treated and control groups that is attributable to a particular program. PSM reduces the observed selection bias emanating from the systematic differences between the treated and control groups [23, 24]. Specifically, selection bias occurs when wealthier and more educated women may have more ANC visits and are also more likely to give birth to normal birth weight infants. In this case, wealthier and more educated women self-selected to have more ANC visits. This study explored the effects of ANC on birth weight and LBW incidence in a cross-sectional dataset after adjusting for socioeconomic confounding variables. The study further estimates the causal relationship between ANC and birth outcomes using the PSM method. This study implements the PSM method by matching women with 4 or more ANC visits to women who did not have 4 or more ANC visits.