Table 1B.

Maternal characteristics of the study population according to the IOM classification

	Underweight	Normal weight	Overweight	Obese
Prepregnancy BMI (kg/m2)	<18.5; n = 1,159 (19.1%)	18.5 to 24.9; n = 4,239 (69.9%)	25 to 29.9; n = 474 (7.8%)	≥30; n = 194 (3.1%)
Maternal age (y)	30.8 ± 4.9**	31.9 ± 4.99	32.7 ± 5.1**	32.6 ± 4.6**
Primiparous rate (%)	57.1**	50.1	37.7**	47.4
Maternal height (cm)	158.2 ± 5.4	157.9 ± 5.5	157.4 ± 5.8	157.0 ± 5.4
Total gestational weight gain (kg)	10.5 ± 4.0	10.7 ± 11.1	8.3 ± 5.9**	5.3 ± 6.6**
Gestational week at delivery	38.3 ± 2.1	38.4 ± 2.0	38.1 ± 2.4*	37.7 ± 2.9**

*p <0.05 vs Normal weight; **p <0.01 vs Normal weight.