TABLE 2.
Odds ratios and 95% confidence intervals for the association of 40-week projected gestational weight gain* with preterm birth subsets 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 | |
| Preterm birth 26–33 weeks and 34–36 weeks vs. term birth ≥37 weeks | ||||||||
| Overall, unadjusted | ||||||||
| 26–33 weeks | 162 | 1.8 (1.4–2.2) | 184 | 1.0 | 151 | 1.1 (0.9–1.4) | 115 | 1.4 (1.1–1.7) |
| 34–36 weeks | 354 | 1.2 (1.1–1.4) | 580 | 1.0 | 479 | 1.1 (1.0–1.3) | 346 | 1.3 (1.1–1.5) |
| By BMI† (GWG * BMI p = .06) | ||||||||
| 26–33 weeks | ||||||||
| Underweight | 6 | 2.2 (0.8–6.1) | 10 | 1.0 | 12 | 1.6 (0.7–3.8) | 6 | 1.3 (0.5–3.7) |
| Normal weight | 61 | 2.0 (1.5–2.9) | 85 | 1.0 | 81 | 1.2 (0.9–1.7) | 49 | 1.2 (0.9–1.7) |
| Overweight | 39 | 1.0 (0.7–1.5) | 58 | 1.0 | 44 | 1.1 (0.7–1.6) | 43 | 1.6 (1.1–2.4) |
| Obese | 56 | 1.5 (1.0–2.4) | 31 | 1.0 | 14 | 0.8 (0.4–1.5) | 17 | 1.4 (0.8–2.5) |
| 34–36 weeks | ||||||||
| Underweight | 14 | 1.3 (0.7–2.5) | 41 | 1.0 | 39 | 1.3 (0.8–2.1) | 16 | 0.9 (0.5–1.7) |
| Normal weight | 143 | 1.3 (1.1–1.6) | 324 | 1.0 | 281 | 1.1 (0.9–1.3) | 189 | 1.3 (1.0–1.5) |
| Overweight | 95 | 1.1 (0.9–1.5) | 128 | 1.0 | 97 | 1.1 (0.8–1.4) | 78 | 1.3 (1.0–1.7) |
| Obese | 102 | 1.0 (0.7–1.3) | 87 | 1.0 | 62 | 1.3 (0.9–1.8) | 63 | 1.9 (1.3–2.6) |
| Spontaneous preterm birth and medically indicated preterm birth vs. term birth ≥37 | ||||||||
| Overall, unadjusted | ||||||||
| Spontaneous preterm birth | 383 | 1.4 (1.2–1.6) | 545 | 1.0 | 447 | 1.1 (1.0–1.3) | 318 | 1.3 (1.1–1.5) |
| Medically indicated preterm birth | 133 | 1.2 (1.0–1.5) | 219 | 1.0 | 183 | 1.1 (0.9–1.4) | 143 | 1.4 (1.2–1.8) |
| By BMI† (GWG * BMI p = .05) | ||||||||
| Spontaneous preterm birth | ||||||||
| Underweight | 11 | 1.0 (0.5–2.0) | 42 | 1.0 | 39 | 1.3 (0.8–2.0) | 17 | 0.9 (0.5–1.7) |
| Normal weight | 157 | 1.6 (1.3–2.0) | 286 | 1.0 | 252 | 1.1 (0.9–1.3) | 163 | 1.2 (1.0–1.5) |
| Overweight | 106 | 1.2 (0.9–1.6) | 130 | 1.0 | 104 | 1.1 (0.9–1.5) | 84 | 1.4 (1.0–1.8) |
| Obese | 109 | 1.1 (0.8–1.4) | 87 | 1.0 | 52 | 1.1 (0.7–1.5) | 54 | 1.6 (1.1–2.3) |
| Medically indicated preterm birth | ||||||||
| Underweight | 9 | 3.7 (1.4–9.5) | 9 | 1.0 | 12 | 1.8 (0.8–4.4) | 5 | 1.3 (0.4–4.0) |
| Normal weight | 47 | 1.1 (0.8–1.6) | 123 | 1.0 | 110 | 1.1 (0.9–1.5) | 75 | 1.3 (1.0–1.8) |
| Overweight | 28 | 0.8 (0.5–1.2) | 56 | 1.0 | 37 | 0.9 (0.6–1.5) | 37 | 1.4 (0.9–2.2) |
| Obese | 49 | 1.3 (0.8–2.1) | 31 | 1.0 | 24 | 1.4 (0.8–2.4) | 26 | 2.1 (1.3–3.7) |
BMI = body mass index; GWG = gestational weight gain; PROM = premature rupture of membranes.
*
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.