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. 2017 Dec 26;172(2):136–142. doi: 10.1001/jamapediatrics.2017.4016

Table 1. Characteristics of Study Population Stratified According to Tertiles of Infant Birth Weight.

Characteristic Infant Birth Weight Tertile
Lowest
(1800-3060 g)
Middle
(3100-3450 g)
Highest
(3500-6000 g)
Pregravid Assessment
Participants, No. 343 434 387
Weeks before pregnancy, median (IQR) 15.4 (2.6 to 46.3) 20.3 (5.6 to 53) 22.4 (5.9 to 60.7)
Age, mean (SD), y 25 (3) 25 (3) 26 (4)
Education, median (IQR), y 10 (9 to 12) 9 (9 to 12) 12 (9 to 12)
Smoking, No. (%) 0 1 (0.2) 5 (1.3)
Weight, mean (SD), kg 47.8 (5.8) 49.8 (6.8) 51.5 (7.1)
BMI, mean (SD) 19.5 (2.1) 20.1 (2.5) 20.7 (2.8)
Waist, mean (SD), m 69 (8) 71 (7) 72 (7)
BP, mean (SD), mm Hg
Systolic 111 (12) 112 (12) 110 (13)
Diastolic 71 (9) 72 (9) 71 (9)
Cholesterol, mean (SD), mg/dL
Total 150.6 (50.2) 150.6 (38.6) 150.6 (46.3)
LDL 81.1 (30.9) 77.2 (27.0) 81.1 (30.9)
HDL 57.9 (19.3) 61.8 (15.4) 57.9 (19.3)
Triglycerides, median (IQR), mg/dL 70.8 (53.1 to 106.2) 79.6 (53.1 to 115.0) 79.6 (61.9 to 115.0)
Blood glucose, mean (SD), mg/dL 81.1 (21.6) 79.3 (21.6) 82.9 (19.8)
During Pregnancy
Weight gain during gestational intervals, median (IQR), kg
Pregravid to 14 wk 1.0 (−1.0 to 4.0) 0.6 (−1.0 to 3.0) 1.5 (−0.5 to 4.0)
14-18 wk 1.5 (0.3 to 2.7) 1.8 (0.8 to 3.0) 2.0 (1.0 to 3.5)
19-23 wk 2.8 (2.0 to 4.0) 3.0 (2.0 to 4.5) 3.0 (2.0 to 4.5)
24-28 wk 3.0 (2.0 to 4.4) 3.0 (2.0 to 4.0) 3.0 (2.0 to 4.7)
29-30 wk 2.5 (1.5 to 4.0) 2.5 (1.5 to 3.7) 2.2 (1.2 to 3.5)
31-32 wk 1.5 (0.5 to 2.0) 1.0 (0.3 to 2.0) 1.0 (0.3 to 2.0)
33-34 wk 1.0 (0 to 2.0) 1.0 (0.5 to 2.0) 1.0 (0.5 to 2.0)
35-36 wk 1.0 (0.5 to 2.0) 1.3 (0.5 to 2.5) 1.0 (0.5 to 2.3)
37-38 wk 1.1 (0.5 to 2.0) 1.0 (0 to 2.0) 1.0 (0.5 to 2.0)
39-40 wk 0.8 (0.3 to 1.5) 1.0 (0 to 1.5) 1.0 (0.4 to 2.0)
At Delivery
Length of gestation, mean (SD), wk 38.9 (1.6) 39.1 (1.1) 39.6 (3.0)
Preterm delivery, No. (%) 32 (9.3) 3 (0.7) 3 (0.8)
Male infant, No. (%)a 154 (45.2) 228 (52.8) 237 (61.4)
Gestational diabetes, No. (%) 3 (0.9) 6 (1.4) 13 (3.4)
Pre-eclampsia, No. (%) 16 (4.7) 10 (2.3) 4 (1.0)
Total maternal weight gain in pregnancy, median (IQR), kg 14.5 (12.0-18.5) 16.0 (13.0-19.5) 17.5 (14.5 to 22.0)

Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); BP, blood pressure; HDL, high-density lipoprotein; IQR, interquartile range; LDL, low-density lipoprotein.

SI conversion factors: To convert total, LDL, and HDL cholesterol to millimoles per liter, multiply by 0.0259; glucose to millimoles per liter, multiply by 0.0555; and triglycerides to millimoles per liter, multiply by 0.0113.

a

Infant sex was missing for 1 woman in the highest tertile and for 2 women in each of the other 2 tertiles.