Body composition in pregnancies of adolescents and mature women and the relationship to birth anthropometry

Abstract

Objective: To investigate differences in body composition between adolescent girls and mature women during pregnancy and the relationship to newborn anthropometry.

Design: A prospective study.

Setting: The antenatal clinic at the University Hospital of the West Indies, Kingston, Jamaica.

Subjects: Four hundred and twenty-five women were invited to join the study. Three hundred and sixty-one women (84.9%) completed the study.

Interventions: Study participants were divided into two groups: adolescents and mature women, who were all less than 15 weeks pregnant and had no systemic illness at the time of entry into the study. A questionnaire was administered which retrieved information on demographics, age, marital status, menstrual history, parity, socio-economic status, medical history and smoking/drinking habits. Anthropometric measurements including weight, height, triceps, biceps, subscapular and suprailiac skinfolds, as well as blood pressure measurements and urine analysis were performed at the first antenatal visit and repeated at 15, 25 and 35 weeks gestation. Anthropometric measurements of the newborn were performed at birth.

Results: There were significant differences between anthropometry and skinfold thickness at the first antenatal visit between the adolescents and the mature women where the adolescents had lower measurements compared to the mature women. In the newborn anthropometry, the only significant difference seen was in the triceps skinfold thickness and the mid-upper arm circumference where the newborn of the adolescents had significantly smaller values (P=0.04; P=0.02, respectively). The percentage fat, fat mass and lean body mass were significantly lower in the adolescent compared to the mature women (P<0.0001), both at the first antenatal visit and at 35 weeks gestation. A greater gain was seen in these measurements throughout the pregnancy in the adolescents (P<0.0001). Linear regression analyses showed that the gain in lean body mass was the most important predictor of birth anthropometry.

Conclusion: Body composition differs in pregnancy between adolescents and mature woman, and if adequate weight and lean body mass are attained, it impacts positively on birth size irrespective of age.