Relationship Between Pre-Pregnancy Body Mass Index, Gestational Weight Gain, and Perinatal Outcomes Among Women Delivering at a General Hospital, Nakhon Si Thammarat Province

This retrospective study examined the associations between pre-pregnancy body mass index (BMI), gestational weight gain (GWG), and perinatal outcomes among women with singleton pregnancies delivering at a general hospital in Nakhon Si Thammarat Province, Thailand. Secondary data were retrieved from the HosXP electronic medical database and delivery records. Of 4659 eligible delivery records, 4051 women met the study criteria and were included in the analysis. Multivariable binary logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). The incidences of preterm birth, small-for-gestational-age (SGA) infants, and below-optimal head circumference (HC) were 6.99%, 18.22%, and 42.85%, respectively. Maternal underweight before pregnancy was significantly associated with increased odds of preterm birth (aOR = 1.60, 95% CI: 1.21-2.12), SGA (aOR = 1.79, 95% CI: 1.44-2.24), and below-optimal HC (aOR = 1.44, 95% CI: 1.18-1.76). Inadequate GWG was also associated with higher odds of SGA (aOR = 1.66, 95% CI: 1.38-2.00) and below-optimal HC (aOR = 1.29, 95% CI: 1.11-1.49). Conversely, maternal overweight/obesity and excessive GWG were associated with lower odds of SGA and below-optimal HC. These findings indicate that pre-pregnancy BMI and GWG were independently associated with adverse perinatal outcomes among Thai women with singleton pregnancies and may provide context-specific evidence to support maternal nutritional assessment and gestational weight monitoring during antenatal care.