Table 4.

Gestational weight gain by BMI class for all term singleton births and for births without complications. Prepregnancy BMI had a significant effect on weight gain, with mean weight gain declining with BMI (r = −0.329, P < 0.001 for all births)

	IOM Recommendations (lb)	N	Mean GWG ± SEM (lb)	Proportion above IOM recommendations
All births		18,217	30.2 ± 0.1	52.9%
Underweight	28–40	551	35.0 ± 0.5	29.4%
Normal weight	25–35	7305	34.5 ± 0.2	44.7%
Overweight	15–25	4623	32.0 ± 0.2	66.4%
Obese class I	11–20	2815	26.0 ± 0.3	63.0%
Obese class II	11–20	1631	21.1 ± 0.4	50.6%
Obese class III	11–20	1292	17.7 ± 0.5	41.3%
Births with no complications		9487	31.6 ± 0.2	52.8%
Underweight	28–40	340	34.1 ± 0.6	26.5%
Normal weight	25–35	4541	34.7 ± 0.2	44.8%
Overweight	15–25	2461	32.6 ± 0.3	68.0%
Obese class I	11–20	1215	26.8 ± 0.5	65.3%
Obese class II	11–20	596	20.0 ± 0.7	48.2%
Obese class III	11–20	334	17.1 ± 1.1	38.9%