A Swansea University led study identifies five primary risk factors associated with delivering a baby with low birth weight. The research highlights how certain conditions around pregnancy can influence newborn weight outcomes and long-term health prospects. Low birth weight is defined as an infant who weighs less than 2500 grams at birth, a threshold linked to increased risk of medical complications and developmental delays as children grow. The findings draw on data from a large population in Wales, offering a detailed picture of how prenatal factors relate to birth weight and subsequent child health trajectories.
Across a dataset covering 693,377 children born in Wales from January 1, 1998, through December 31, 2018, researchers identified several patterns. The study shows that multiple pregnancies, such as twins or triplets, heighten the chance of having a baby with low birth weight. In addition, pregnancies spaced less than one year apart also increase risk, likely reflecting insufficient time for maternal recovery before the next pregnancy. Disturbances in the mother’s physical or mental health during or around pregnancy emerge as important contributors to lower birth weight as well.
Among maternal health factors, diabetes, anemia, depression, severe mental illness, anxiety, and the use of antidepressants during pregnancy stand out as particularly influential. Other risk factors include smoking during pregnancy, hospital admissions related to alcohol or other substances, experiences of domestic violence, the age of the mother (especially those 35 and older), and living in economically disadvantaged neighborhoods. These interconnected elements underscore how maternal health, behavior, and social conditions collectively shape birth outcomes and early child development.
Experts emphasize that recognizing these risk factors does not determine destiny. Instead, it supports targeted prenatal care and public health strategies designed to reduce low birth weight through prevention and early intervention. By focusing on maternal health optimization, smoking cessation and substance use support, mental health treatment for pregnant individuals, and social services access, health systems can improve birth weights and long-term health for children. The Swansea University study contributes to a growing body of evidence that stronger supports and timely medical attention during pregnancy can influence birth outcomes at scale, benefiting families and communities across Wales and beyond. In summary, the work highlights how a combination of medical, behavioral, and socioeconomic factors converges to affect newborn weight and later health trajectories, guiding policy makers and clinicians toward more effective, comprehensive care for expectant mothers.