Maternal and child characteristics by maternal prepregnancy body mass index (BMI), Avon Longitudinal Study of Parents and Children (n=4324)
| Maternal prepregnancy BMI | |||
| Normal weight (BMI 18.5 to <25) | Overweight (BMI 25 to <30) | Obese (BMI≥30) | |
| n=3397 | n=684 | n=243 | |
| Offspring full-scale IQ*, mean (SD) | 107 (16) | 103 (16) | 101 (18) |
| Offspring verbal IQ*, mean (SD) | 110 (17) | 106 (16) | 105 (17) |
| Offspring performance IQ*, mean (SD) | 102 (17) | 99 (17) | 96 (18) |
| Male child, % | 50 | 49 | 48 |
| Maternal age at delivery in years, mean (SD) | 29.4 (4.3) | 29.1 (4.5) | 28.7 (4.8) |
| Parity, % (valid %†) | |||
| Nulliparous | 48 (49) | 47 (48) | 41 (42) |
| Multiparous | 50 (51) | 51 (52) | 57 (58) |
| Missing (n=83) | 1.9 | 2.2 | 2.1 |
| Married, % (valid %†) | |||
| Yes | 85 (85) | 86 (86) | 89 (89) |
| No | 15 (15) | 13 (13) | 11 (11) |
| Missing (n=10) | 0.2 | 0.3 | 0 |
| Pre-existing hypertension, % (valid %†) | |||
| Yes | 3.3 (3.3) | 6.3 (6.5) | 9.9 (10) |
| No | 95 (97) | 91 (94) | 89 (90) |
| Missing (n=90) | 2.0 | 2.8 | 1.2 |
| Smoked tobacco during pregnancy, % (valid %†) | |||
| Yes | 16 (18) | 21 (23) | 18 (20) |
| No | 72 (82) | 70 (77) | 69 (80) |
| Missing (n=497) | 12 | 10 | 14 |
| Index of alcohol consumption during pregnancy‡, mean (SD) | 1.54 (1.33) | 1.46 (1.37) | 1.28 (1.22) |
| Missing, % (n=166) | 3.8 | 3.9 | 3.7 |
| SES index§, mean (SD) | 14.7 (3.2) | 13.8 (3.3) | 12.9 (3.4) |
| Missing, % (n=904) | 20 | 23 | 29 |
| Pre-eclampsia¶, % (valid %†) | |||
| Yes | 1.6 (1.7) | 2.8 (2.8) | 8.6 (8.7) |
| No | 98 (98) | 97 (97) | 91 (91) |
| Missing (n=18) | 0.4 | 0.6 | 0.4 |
| Caesarean delivery, % (valid %†) | |||
| Yes | 8.6 (8.8) | 13 (13) | 22 (23) |
| No | 89 (91) | 86 (87) | 76 (77) |
| Missing (n=82) | 2.0 | 1.6 | 1.6 |
| Preterm delivery, % | 4.6 | 2.9 | 7.4 |
| Duration of breastfeeding, % (valid %†) | |||
| Never or <6 months | 54 (57) | 62 (65) | 72 (77) |
| ≥6 months | 41 (43) | 33 (35) | 22 (23) |
| Missing (n=222) | 5.1 | 5.1 | 6.2 |
| Average gestational weight gain per week in kilograms, mean (SD) | 0.47 (0.14) | 0.46 (0.18) | 0.36 (0.22) |
| Missing, % (n=311) | 7.3 | 6.7 | 7.4 |
| Birth weight in grams, mean (SD) | 3441 (500) | 3539 (525) | 3540 (672) |
| Missing, % (n=55) | 1.3 | 1.2 | 1.6 |
*Psychologist-assessed using abbreviated form of the Wechsler Intelligence Scale for Children-III at a mean age of 8.6 years (SD 0.26).
†Excludes missing values.
‡Ranges from 0 to 6; higher values indicate more alcohol consumption.
§Ranges from 4 to 20; higher values indicate higher SES.
¶With or without pre-existing hypertension.
SES, socioeconomic status.