Table 1.
Characteristics of complete case and eligible study populations
| Eligible population | Complete case population | |||||
| Gest. age (days) | Birth weight (g) | Gestational age (days) | Birth weight (g) | |||
| No. (%) | Mean (SD) | Mean (SD) | No. (%) | Mean (SD) | Mean (SD) | |
| Total | 315 177 (100%) | 276 (12) | 3328 (515) | 81 968 (100%) | 276 (12) | 3339 (501) |
| Birth weight (g) | ||||||
| <1500 | 2141 (0.7%) | 196 (27) | 966 (354) | 445 (0.5%) | 198 (28) | 983 (491) |
| 1500–1999 | 2413 (0.8%) | 238 (15) | 1800 (142) | 612 (0.7%) | 239 (15) | 1803 (528) |
| 2000–2499 | 10 036 (3.2%) | 258 (14) | 2312 (134) | 2484 (3%) | 258 (13) | 2314 (477) |
| ≥2500 | 300 586 (95.4%) | 277 (9) | 3391 (423) | 78 426 (95.7%) | 277 (9) | 3396 (502) |
| Gestational age (weeks) | ||||||
| <320 | 2333 (0.7%) | 195 (23) | 1108 (527) | 487 (0.6%) | 196 (23) | 1134 (491) |
| 320–346 | 3950 (1.3%) | 237 (6) | 2144 (424) | 961 (1.2%) | 237 (6) | 2136 (470) |
| 350–366 | 10 907 (3.5%) | 253 (4) | 2686 (431) | 2760 (3.4%) | 253 (4) | 2692 (489) |
| ≥370 | 297 987 (94.5%) | 278 (8) | 3385 (440) | 77 760 (94.9%) | 278 (8) | 3390 (502) |
| Sex | ||||||
| Female | 152 757 (48.5%) | 276 (12) | 3260 (494) | 39 823 (48.6%) | 276 (11) | 3267 (502) |
| Male | 162 420 (51.5%) | 275 (13) | 3392 (525) | 42 145 (51.4%) | 276 (12) | 3406 (501) |
| Birth rank | ||||||
| 1 | 155 739 (49.4%) | 276 (13) | 3262 (519) | 37 763 (46.1%) | 276 (13) | 3267 (498) |
| 2 | 115 440 (36.6%) | 275 (11) | 3382 (497) | 32 315 (39.4%) | 276 (11) | 3386 (504) |
| 3 | 34 364 (10.9%) | 275 (11) | 3418 (509) | 9360 (11.4%) | 275 (11) | 3430 (508) |
| ≥4 | 9634 (3.1%) | 275 (12) | 3438 (537) | 2530 (3.1%) | 275 (11) | 3459 (498) |
| Civil status | ||||||
| Married | 250 055 (79.3%) | 276 (12) | 3345 (508) | 69 465 (84.7%) | 276 (12) | 3349 (501) |
| Not married | 65 122 (20.7%) | 276 (14) | 3262 (536) | 12 503 (15.3%) | 276 (13) | 3283 (503) |
| Maternal age (years) | ||||||
| Mean (SD) | 31.7 (5.0) | 32.2 (4.7) | ||||
| <20 | 2679 (0.8%) | 275 (16) | 3224 (554) | 0 (0%) | – | – |
| ≥20–25 | 28 615 (9.1%) | 277 (12) | 3317 (511) | 5417 (6.6%) | 277 (12) | 3337 (491) |
| ≥25–30 | 82 620 (26.2%) | 276 (12) | 3330 (506) | 20 771 (25.3%) | 276 (12) | 3337 (500) |
| ≥30–35 | 118 303 (37.5%) | 276 (12) | 3335 (510) | 32 771 (40%) | 276 (12) | 3341 (505) |
| ≥35–40 | 67 914 (21.5%) | 275 (12) | 3333 (523) | 19 052 (23.2%) | 275 (11) | 3345 (497) |
| ≥40 | 15 046 (4.8%) | 273 (14) | 3286 (555) | 3957 (4.8%) | 273 (14) | 3295 (512) |
| Nationality mother | ||||||
| Switzerland | 194 570 (61.7%) | 276 (12) | 3322 (511) | 55 591 (67.8%) | 276 (12) | 3331 (502) |
| Southern Europe | 23 585 (7.5%) | 275 (12) | 3251 (494) | 5761 (7%) | 276 (11) | 3261 (502) |
| Western Europe | 26 005 (8.3%) | 276 (12) | 3348 (516) | 6495 (7.9%) | 276 (12) | 3359 (508) |
| Northern Europe | 3695 (1.2%) | 276 (13) | 3418 (510) | 850 (1%) | 276 (13) | 3414 (508) |
| Eastern Europe | 38 762 (12.3%) | 276 (13) | 3397 (523) | 8035 (9.8%) | 276 (12) | 3422 (499) |
| Other | 28 560 (9.1%) | 275 (14) | 3313 (535) | 5236 (6.4%) | 275 (13) | 3332 (492) |
| Nationality father | ||||||
| Switzerland | 191 589 (60.8%) | 276 (12) | 3329 (506) | 55 432 (67.6%) | 276 (12) | 3336 (502) |
| Southern Europe | 31 466 (10%) | 275 (12) | 3256 (493) | 7970 (9.7%) | 275 (11) | 3262 (504) |
| Western Europe | 26 954 (8.6%) | 276 (12) | 3353 (518) | 6661 (8.1%) | 276 (12) | 3367 (514) |
| Northern Europe | 3911 (1.2%) | 276 (12) | 3406 (510) | 887 (1.1%) | 276 (13) | 3393 (499) |
| Eastern Europe | 35 387 (11.2%) | 276 (13) | 3397 (528) | 7229 (8.8%) | 276 (12) | 3418 (489) |
| Other | 21 077 (6.7%) | 276 (13) | 3307 (531) | 3789 (4.6%) | 276 (12) | 3319 (497) |
| Missing | 4793 (1.5%) | 272 (23) | 3148 (693) | – | – | – |
| Education mother | ||||||
| Tertiary | 42 088 (13.4%) | 276 (12) | 3344 (500) | 33 505 (40.9%) | 276 (12) | 3347 (500) |
| Secondary | 48 878 (15.5%) | 276 (12) | 3328 (509) | 38 382 (46.8%) | 276 (12) | 3331 (502) |
| Compulsory | 14 642 (4.6%) | 275 (13) | 3329 (534) | 10 081 (12.3%) | 275 (13) | 3336 (503) |
| Unknown (age <20 years) | 2679 (0.8%) | 275 (16) | 3224 (554) | 0 (0%) | – | – |
| Missing | 206 890 (65.6%) | 276 (12) | 3326 (517) | – | – | – |
| Education father | ||||||
| Tertiary | 49 848 (15.8%) | 276 (12) | 3348 (497) | 40 345 (49.2%) | 276 (12) | 3350 (500) |
| Secondary | 41 301 (13.1%) | 276 (12) | 3323 (511) | 32 118 (39.2%) | 276 (12) | 3327 (504) |
| Compulsory | 13 731 (4.4%) | 276 (12) | 3323 (514) | 9505 (11.6%) | 276 (12) | 3330 (500) |
| Missing | 210 297 (66.7%) | 276 (13) | 3325 (519) | – | – | – |
| Altitude (m) | ||||||
| Mean (SD) | 515 (189) | 511 (180) | ||||
| Urbanisation | ||||||
| Urban | 96 643 (30.7%) | 276 (13) | 3326 (517) | 22 770 (27.8%) | 276 (12) | 3334 (502) |
| Peri-urban | 138 826 (44%) | 275 (12) | 3329 (514) | 36 629 (44.7%) | 276 (12) | 3339 (502) |
| Rural | 79 708 (25.3%) | 276 (12) | 3329 (512) | 22 569 (27.5%) | 276 (12) | 3343 (500) |
| Language region | ||||||
| German | 223 586 (70.9%) | 276 (12) | 3348 (515) | 54 106 (66%) | 276 (12) | 3362 (502) |
| French | 80 068 (25.4%) | 275 (12) | 3283 (512) | 23 579 (28.8%) | 275 (12) | 3296 (501) |
| Italian | 11 523 (3.7%) | 275 (12) | 3252 (494) | 4283 (5.2%) | 275 (11) | 3268 (500) |
| Socioeconomic position | ||||||
| First quintile | 63 230 (20.1%) | 276 (12) | 3318 (522) | 15 752 (19.2%) | 276 (12) | 3331 (501) |
| Second quintile | 63 199 (20.1%) | 276 (12) | 3324 (519) | 16 034 (19.6%) | 276 (12) | 3334 (505) |
| Tthird quintile | 63 156 (20%) | 276 (12) | 3329 (516) | 16 555 (20.2%) | 276 (12) | 3337 (500) |
| Fourth quintile | 62 970 (20%) | 276 (12) | 3335 (509) | 16 933 (20.7%) | 276 (12) | 3344 (500) |
| Fifth quintile | 62 622 (19.9%) | 276 (12) | 3335 (507) | 16 694 (20.4%) | 276 (12) | 3346 (502) |