Characteristics by rapid infant weight gain from 0 to 18 months.

	Rapid infant weight gain from 0 to 18 months (N=609)
	Not Rapid	Rapid
Prepregnancy body mass index (kg/m2), %
Underweight (<18.5)	54	46
Normal weight (18.5–24.9)	55	45
Overweight (25.9–29.9)	55	45
Obese (≥30.0)	60	40
Maternal race/ethnicity, %
White	59	41
Black	52	48
Income level ($/month), %
<400	55	45
≥400	57	43
Parity
Nulliparous	54	46
Multiparous	57	43
Pattern of prenatal smoking, % *
Never used in pregnancy	64	36
First trimester use only	51	49
Second and/or third trimester use	49	51
Pattern of prenatal alcohol use, %
Never used in pregnancy	52	48
First trimester use only	54	46
Second and/or third trimester use	61	39
Pattern of prenatal marijuana use, %
Never used in pregnancy	58	42
First trimester use only	56	44
Second and/or third trimester use	47	53
Gestational age at delivery (weeks), (%) *
<37 weeks	4	96
≥37 weeks	60	40
Birth weight for gestational age z-score, % *
Small for age (<10th percentile)	25	75
Appropriate for age (10th to 90th percentile)	60	40
Large for age (>90th percentile)	91	9
Infant sex, %
Female	55	45
Male	56	44
Ever breastfed infant, %
Yes	63	37
No	54	47

^*Pearson chi-square test p<0.05