Table 1.
Characteristics of women with spontaneous singleton births by early pregnancy body mass index, n = 29,709
| Characteristics | Underweight | Normal | Overweight | Obese | p * |
|---|---|---|---|---|---|
| n = 2,100 | n = 20,081 | n = 5,427 | n = 2,101 | ||
| Age at delivery, mean (SD) | 24.2 (4.1) | 26.4 (4.8) | 28.4 (5.2) | 29.4 (5.0) | <0.001 |
| Age at delivery, n (%) | <0.001 | ||||
| ≤ 19 | 239 (11.4) | 1,257 (6.3) | 167 (3.1) | 29 (1.4) | |
| 20-24 | 965 (46.0) | 6,510 (32.4) | 1,230 (22.7) | 345 (16.4) | |
| 25-29 | 668 (31.8) | 7,214 (35.9) | 1,812 (33.4) | 703 (33.5) | |
| 30-34 | 191 (9.1) | 3,874 (19.3) | 1,485 (27.4) | 670 (31.9) | |
| ≥35 | 37 (1.8) | 1,226 (6.1) | 733 (13.5) | 354 (16.8) | |
| Ethnicity, n (%) | 0.039 | ||||
| Russian | 1,978 (94.2) | 18,957 (94.4) | 5,067 (93.4) | 1,979 (94.2) | |
| Other | 122 (5.8) | 1,124 (5.6) | 360 (6.6) | 122 (5.8) | |
| Education, n (%) | <0.001 | ||||
| Incomp. secondary or less | 81 (3.9) | 448 (2.2) | 119 (2.2) | 47 (2.2) | |
| Secondary | 745 (35.5) | 5,700 (28.4) | 1,450 (26.7) | 582 (27.7) | |
| Vocational | 624 (29.7) | 6,287 (31.3) | 1,998 (36.8) | 769 (36.6) | |
| Higher | 634 (30.2) | 7,516 (37.4) | 1,832 (33.8) | 690 (32.8) | |
| Unknown | 16 (0.8) | 130 (0.6) | 28 (0.5) | 13 (0.6) | |
| Marital status, n (%) | <0.001 | ||||
| Married | 1,540 (73.3) | 15,334 (76.4) | 4,038 (79.4) | 1,706 (81.2) | |
| Unmarried | 560 (26.7) | 4,747 (23.6) | 1,119 (20.6) | 395 (18.8) | |
| Residents, n (%) | <0.001 | ||||
| Urban | 1,671 (79.6) | 16,160 (80.5) | 4,276 (78.8) | 1,587 (75.5) | |
| Rural | 429 (20.4) | 3,921 (19.5) | 1,151 (21.2) | 514 (24.5) | |
| Smoking before pregnancy, n (%) | <0.001 | ||||
| Yes | 490 (23.3) | 4,345 (21.6) | 1,269 (23.4) | 536 (25.5) | |
| No | 1,610 (76.7) | 15,736 (78.4) | 4,158 (76.6) | 1,565 (74.5) | |
| Alcohol abuse during pregnancy, n (%) | 0.261† | ||||
| Yes | 7 (0.3) | 31 (0.2) | 9 (0.2) | 5 (0.2) | |
| No | 2,093 (99.7) | 20,050 (99.8) | 5,418 (99.8) | 2,096 (99.8) | |
| Parity, n (%) | <0.001 | ||||
| 0 | 1,536 (73.1) | 12,053 (60.0) | 2,350 (43.3) | 725 (34.5) | |
| 1 | 501 (23.9) | 7,027 (35.0) | 2,540 (46.8) | 1,088 (51.8) | |
| 2+ | 63 (3.0) | 1,001 (5.0) | 537 (9.9) | 288 (13.7) | |
| Diabetes mellitus (types 1 or 2 or gest.), n (%) | 0.002† | ||||
| Yes | 0 (0.0) | 27 (0.1) | 8 (0.1) | 9 (0.4) | |
| No | 2,100 (100.0) | 20,054 (99.9) | 5,419 (99.9) | 2,092 (99.6) | |
| Hyperemesis gravidarum, n (%) | <0.001 | ||||
| Yes | 62 (3.0) | 1,223 (6.1) | 631 (11.6) | 377 (17.9) | |
| No | 2,038 (97.0) | 18,858 (93.9) | 4,796 (88.4) | 1,724 (82.1) | |
| Preeclampsia/eclampsia, n (%) | 0.003† | ||||
| Yes | 1 (<0.1) | 20 (0.1) | 6 (0.1) | 8 (0.4) | |
| No | 2,099 (100.0) | 20,061 (99.9) | 5,421 (99.9) | 2,093 (99.6) | |
| Excessive weight gain during pregnancy, n (%) | <0.001 | ||||
| Yes | 98 (4.7) | 1,201 (6.0) | 387 (7.1) | 137 (6.5) | |
| No | 2,002 (95.3) | 18,880 (94.0) | 5,040 (92.9) | 1,964 (93.5) | |
*Calculated using analysis of variances (for age as an interval variable), or chi-squared test (other variables).
†25% of cells in the cross table have expected count less than 5.