Table 1 Characteristics of participants
|  | Frequency of breakfast intake (pre- to early pregnancy) | p–valuea | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Total | Everyday | 5–6 times/week | 3–4 times/week | 0–2 times/week | |||||||
(n = 16,820) | (n = 12,442) | (n = 1673) | (n = 1165) | (n = 1540) | |||||||
Pregnant women | n (%) or mean (SD) | Â | |||||||||
Age at delivery (years) | |||||||||||
  < 25 | 1494 | (8.9) | 757 | (6.1) | 223 | (13.3) | 197 | (16.9) | 317 | (20.6) |  < 0.001 |
 25–29 | 4632 | (27.5) | 3160 | (25.4) | 550 | (32.9) | 398 | (34.2) | 524 | (34.0) | |
 30–34 | 6174 | (36.7) | 4805 | (38.6) | 561 | (33.5) | 374 | (32.1) | 434 | (28.2) | |
  ≥ 35 | 4520 | (26.9) | 3720 | (29.9) | 339 | (20.3) | 196 | (16.8) | 265 | (17.2) | |
Pre-pregnancy BMI (kg/m2) | |||||||||||
  < 18.5 | 2213 | (13.2) | 1604 | (12.9) | 220 | (13.2) | 168 | (14.4) | 221 | (14.4) |  < 0.001 |
 18.5–24.9 | 12,427 | (73.9) | 9311 | (74.8) | 1230 | (73.5) | 814 | (69.9) | 1072 | (69.6) | |
  ≥ 25.0 | 2180 | (13.0) | 1527 | (12.3) | 223 | (13.3) | 183 | (15.7) | 247 | (16.0) | |
Smoking status | |||||||||||
 Never | 10,213 | (60.7) | 7987 | (64.2) | 942 | (56.3) | 603 | (51.8) | 681 | (44.2) |  < 0.001 |
 Quit before pregnancy | 3880 | (23.1) | 2938 | (23.6) | 385 | (23.0) | 248 | (21.3) | 309 | (20.1) | |
 Quit after pregnancy | 2333 | (13.9) | 1343 | (10.8) | 289 | (17.3) | 262 | (22.5) | 439 | (28.5) | |
 Current | 394 | (2.3) | 174 | (1.4) | 57 | (3.4) | 52 | (4.5) | 111 | (7.2) | |
Alcohol consumption | |||||||||||
 Never | 7737 | (46.0) | 5875 | (47.2) | 740 | (44.2) | 502 | (43.1) | 620 | (40.3) |  < 0.001 |
 Former | 5788 | (34.4) | 4156 | (33.4) | 614 | (36.7) | 415 | (35.6) | 603 | (39.2) | |
 Current | 3295 | (19.6) | 2411 | (19.4) | 319 | (19.1) | 248 | (21.3) | 317 | (20.6) | |
 Parity ≥ 1 | 9016 | (53.6) | 7527 | (60.5) | 610 | (36.5) | 408 | (35.0) | 471 | (30.6) |  < 0.001 |
Employment status | |||||||||||
 Employed | 12,682 | (75.4) | 9275 | (74.6) | 1286 | (76.9) | 909 | (78.0) | 1212 | (78.7) |  < 0.001 |
 Unemployed | 4138 | (24.6) | 3167 | (25.5) | 387 | (23.1) | 256 | (22.0) | 328 | (21.3) | |
Morning sickness | |||||||||||
 Never | 2374 | (14.1) | 1698 | (13.7) | 249 | (14.9) | 173 | (14.9) | 254 | (16.5) |  < 0.001 |
 Nausea only | 7489 | (44.5) | 5713 | (45.9) | 684 | (40.9) | 492 | (42.2) | 600 | (39.0) | |
 Vomiting, able to eat | 5163 | (30.7) | 3769 | (30.3) | 553 | (33.1) | 363 | (31.2) | 478 | (31.0) | |
 Vomiting, unable to eat | 1794 | (10.7) | 1262 | (10.1) | 187 | (11.2) | 137 | (11.8) | 208 | (13.5) | |
 Insomnia | 5885 | (35.0) | 4105 | (33.0) | 636 | (38.0) | 476 | (40.9) | 668 | (43.4) |  < 0.001 |
Folic acid supplementation | |||||||||||
 Yes | 9460 | (56.2) | 6955 | (55.9) | 991 | (59.2) | 653 | (56.1) | 861 | (55.9) | 0.08 |
 No | 7360 | (43.8) | 5487 | (44.1) | 682 | (40.8) | 512 | (44.0) | 679 | (44.1) | |
 Energy intake (kcal/day) | 1635 | (529) | 1669 | (517) | 1600 | (524) | 1567 | (570) | 1451 | (554) |  < 0.001 |
Infant | |||||||||||
 Birth weight (g) | 3071 | (371) | 3076 | (371) | 3074 | (357) | 3044 | (383) | 3049 | (371) | 0.003 |
 Boy | 8606 | (51.2) | 6344 | (51.0) | 872 | (52.1) | 589 | (50.6) | 801 | (52.0) | 0.71 |