Small-for-gestational age and its association with maternal blood glucose, body mass index and stature: a perinatal cohort study among Chinese women

OBJECTIVE: To examine whether maternal low blood glucose (BG), low body mass index (BMI) and small stature have a joint effect on the risk of delivery of a small-for-gestational age (SGA) infant. DESIGN: Women from a perinatal cohort were followed up from receiving perinatal healthcare to giving birth. SETTING: Beichen District, Tianjin, China between June 2011 and October 2012. PARTICIPANTS: 1572 women aged 19–39 years with valid values of stature, BMI and BG level at gestational diabetes mellitus screening (gestational weeks 24–28), glucose challenge test <7.8 mmol/L and singleton birth (≥37 weeks’ gestation). MAIN OUTCOME MEASURES: SGA was defined as birth weight <10th centile for gender separated gestational age of Tianjin singletons. RESULTS: 164 neonates (10.4%) were identified as SGA. From multiple logistic regression models, the ORs (95% CI) of delivery of SGA were 0.84 (0.72 to 0.98), 0.61 (0.49 to 0.74) and 0.64 (0.54 to 0.76) for every 1 SD increase in maternal BG, BMI and stature, respectively. When dichotomises, maternal BG (<6.0 vs ≥6.0 mmol/L), BMI (<24 vs ≥24 kg/m(2)) and stature (<160.0 vs ≥160.0 cm), those with BG, BMI and stature all in the lower categories had ∼8 times higher odds of delivering an SGA neonate (OR (95% CI) 8.01 (3.78 to 16.96)) relative to the reference that had BG, BMI and stature all in the high categories. The odds for an SGA delivery among women who had any 2 variables in the lower categories were ∼2–4 times higher. CONCLUSIONS: Low maternal BG is associated with an increased risk of having an SGA infant. The risk of SGA is significantly increased when the mother is also short and has a low BMI. This may be a useful clinical tool to identify women at higher risk for having an SGA infant at delivery.