TABLE 1.

Odds ratios and 95% confidence intervals for the association of 40-week projected gestational weight gain^* with preterm birth (<37 weeks’ gestation) among singleton births to New York City residents delivering in New York State, 1995 to 2003, n = 33,872

	40-Week projected gestational weight gain
	Cases, n	0–9 kg	Cases, n	10–14 kg	Cases, n	15–19 kg	Cases, n	20+ kg
Overall, unadjusted	516	1.4 (1.2–1.5)	764	1.0	630	1.1 (1.0–1.2)	461	1.3 (1.2–1.5)
By BMI† (GWG* BMI p = .05)
Underweight	20	1.5 (0.9–2.6)	51	1.0	51	1.4 (0.9–2.1)	22	1.0 (0.6–1.7)
Normal weight	204	1.5 (1.2–1.7)	409	1.0	362	1.1 (1.0–1.3)	238	1.3 (1.1–1.5)
Overweight	134	1.1 (0.9–1.4)	186	1.0	141	1.1 (0.9–1.4)	121	1.4 (1.1–1.8)
Obese	158	1.1 (0.9–1.4)	118	1.0	76	1.2 (0.9–1.6)	80	1.7 (1.3–2.3)
By race/ethnicity† (GWG * race p = .53)
Non-Hispanic white	161	1.2 (1.0–1.5)	277	1.0	239	1.1 (0.9–1.3)	197	1.5 (1.2–1.8)
Non-Hispanic black	233	1.3 (1.1–1.6)	275	1.0	232	1.3 (1.0–1.5)	169	1.3 (1.1–1.7)
Hispanic	86	1.2 (0.9–1.6)	125	1.0	95	1.0 (0.8–1.3)	74	1.1 (0.8–1.4)
Asian	36	1.0 (0.7–1.5)	87	1.0	64	1.1 (0.7–1.5)	21	1.0 (0.6–1.6)

BMI = body mass index; GWG = gestational weight gain.

^*40-week projected gestational weight gain is the average weekly gestational weight gain multiplied by 40 to approximate the amount of weight that would have been gained had all women delivered at 40 weeks

^†Adjusted for BMI, race/ethnicity, maternal age, parity, education, tobacco.