Table 1. Description of the ELFE population (N = 16,395) after excluding women with a medical history or missing data on body mass index (BMI), in the whole sample and by BMI at the beginning of pregnancy.
| Characteristic | Missing data N (%) |
Population (N = 16,395) |
BMI < 25 kg/m2 (N = 12,058) |
BMI ≥ 25 kg/m2 (N = 4,337) |
|---|---|---|---|---|
| Mother | ||||
| Maternal age (years), n (%) | 4 (0.02) | |||
| <25 | 2,225 (13.6) | 1,582 (13.1) | 643 (14.8) | |
| 26–35 | 11,085 (67.6) | 8,273 (68.6) | 2,812 (64.8) | |
| >35 | 3,081 (18.8) | 2,199 (18.2) | 882 (20.3) | |
| Born in France, n (%) | 12 (0.07) | 14,272 (87.1) | 10,601 (88.0) | 3,671 (84.8) |
| Maternal education, n (%) | 1 (0.01) | |||
| Lower secondary | 1,368 (8.3) | 847 (7.0) | 521 (12.0) | |
| Upper secondary | 5,711 (34.8) | 3,841 (31.9) | 1,870 (43.1) | |
| Post-secondary | 3,663 (22.3) | 2,675 (22.2) | 988 (22.8) | |
| Tertiary | 5,652 (34.5) | 4,694 (38.9) | 958 (22.1) | |
| Activity status, n (%) | 351 (2.1) | |||
| Employed or student | 12,935 (80.6) | 9,839 (83.2) | 3,096 (73.3) | |
| Staying at home | 3,109 (19.4) | 1,982 (16.8) | 1,127 (26.7) | |
| Health insurance coverage, n (%) | 55 (0.3) | |||
| For precarious situations | 1,343 (8.2) | 853 (7.1) | 490 (11.4) | |
| Regular | 14,997 (91.8) | 11,170 (92.9) | 3,827 (88.6) | |
| Living with a partner, n (%) | 73 (0.4) | 15,450 (94.7) | 11,409 (95.1) | 4,041 (93.5) |
| Smoking before pregnancy, n (%) | 49 (0.3) | 6,964 (42.6) | 5,211 (43.3) | 1,753 (40.6) |
| Pregnancy | ||||
| Primiparous, n (%) | 31 (0.2) | 7,313 (44.7) | 5,680 (47.2) | 1,633 (37.7) |
| Pregnancy caregiver, n (%) | 112 (0.7) | |||
| Gynecologist | 10,718 (65.8) | 7,958 (66.4) | 2,760 (64.1) | |
| Midwife | 2,034 (12.5) | 1,455 (12.1) | 579 (13.4) | |
| General practitioner or none | 907 (5.6) | 638 (5.3) | 269 (6.2) | |
| Multiple professionals | 2,624 (16.1) | 1,926 (16.1) | 698 (16.2) | |
| Smoking during pregnancy, n (%) | 104 (0.6) | 3,281 (20.1) | 2,446 (20.4) | 835 (19.4) |
| Weight variation in the year before pregnancy, n (%) | 2,102 (12.8) | |||
| Weight loss | 1,415 (9.9) | 806 (7.7) | 609 (16.2) | |
| Stable weight | 11,210 (78.4) | 8,952 (85.0) | 2,258 (60.0) | |
| Weight gain | 1,668 (11.7) | 771 (7.3) | 897 (23.8) | |
| Restrictive diet before pregnancy, n (%) | 1,974 (12.0) | 2,381 (16.5) | 1,202 (11.3) | 1,179 (31.1) |
| Pre-pregnancy BMI category | 0 (0) | |||
| Underweight | 1,292 (7.9) | 1,292 (10.7) | — | |
| Normal | 10,766 (65.7) | 10,766 (89.3) | — | |
| Overweight | 2,791 (17.0) | — | 2,791 (64.4) | |
| Obesity | 1,546 (9.4) | — | 1,546 (35.6) | |
| Gestational weight gain (kg), mean ± SD | 114 (0.7) | 13.2 ± 5.5 | 13.9 ± 4.8 | 11.2 ± 7 |
| Newborn | ||||
| Gestational age of birth (WA), mean ± SD | 111 (0.7) | 39.6 ± 1.4 | 39.6 ± 1.4 | 39.7 ± 1.4 |
| Birth weight Audipog z-scorea, mean ± SD | 322 (2.0) | 0.08 ± 1.0 | 0.01 ± 0.9 | 0.27 ± 1.0 |
| Birth weight categoryb, n (%) | 322 (2.0) | |||
| Small for gestational age | 1,280 (8.0) | 1,012 (8.6) | 268 (6.3) | |
| Appropriate for gestational age | 13,238 (82.4) | 9,866 (83.5) | 3,372 (79.2) | |
| Large for gestational age | 1,555 (9.7) | 939 (7.9) | 616 (14.5) |
aBirth weight z-score according to the French Audipog reference [26].
bBirth weight categories to assess fetal growth: small for gestational age (<10th percentile), appropriate for gestational age (10th to 90th percentile), and large for gestational age (>90th percentile) according to the French Audipog reference.
WA, weeks’ amenorrhea.