|  |  |  | Total folate intake (μg/d) | Initiation of preconceptional folic acid supplementation, n (%) | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 |  | n | (%) | Median (IQR) | p 1 | >8 w | 0-8 w | No | p 2 | ||||
Total |  | 66014 | (100) | 313 | (167–558) |  | 16023 | (24) | 12877 | (20) | 37114 | (56) |  |
 | <25 | 7561 | (12) | 258 | (154–528) |  | 849 | (11) | 942 | (13) | 5770 | (76) |  |
Maternal age in years | 25-29 | 22672 | (34) | 324 | (170–562) | <0.0001 | 5121 | (23) | 4821 | (21) | 12730 | (56) | <0.0001 |
30-34 | 27993 | (42) | 319 | (168–562) |  | 7726 | (28) | 5894 | (21) | 14373 | (51) |  | |
>34 | 7788 | (12) | 315 | (170–562) |  | 2327 | (30) | 1220 | (16) | 4241 | (55) |  | |
Pre-pregnancy BMI in kg/m2 | <18.5 | 19\31 | (3) | 343 | (179–575) |  | 432 | (22) | 351 | (18) | 1148 | (60) |  |
18.5-24.9 | 42611 | (65) | 328 | (173–566) | <0.0001 | 10773 | (25) | 8637 | (20) | 23201 | (54) | <0.0001 | |
25-30 | 13839 | (21) | 289 | (160–548) |  | 3228 | (23) | 2651 | (19) | 7960 | (58) |  | |
≥30 | 5970 | (9) | 268 | (151–533) |  | 1305 | (22) | 953 | (16) | 3712 | (62) |  | |
Missing | 1663 | (3) | 250 | (156–517) |  | 285 | (17) | 285 | (17) | 1093 | (66) |  | |
 | 0 | 34825 | (53) | 355 | (180–580) |  | 9324 | (27) | 6480 | (19) | 19021 | (55) |  |
 | 1 | 20028 | (30) | 281 | (159–545) | <0.0001 | 4528 | (23) | 4531 | (23) | 10969 | (55) | <0.0001 |
Parity | 2 | 9005 | (14) | 245 | (156–517) |  | 1787 | (20) | 1570 | (17) | 5648 | (63) |  |
 | 3+ | 2101 | (3) | 224 | (149–451) |  | 370 | (18) | 285 | (14) | 1446 | (69) |  |
 | Missing | 55 | (0.1) | 353 | (166–566) |  | 14 | (26) | 11 | (20) | 30 | (55) |  |
Marita status | Yes | 63518 | (96) | 315 | (168–559) | <0.0001 | 15714 | (25) | 12661 | (20) | 35143 | (55) | <0.0001 |
No | 2496 | (4) | 266 | (158–531) |  | 309 | (12) | 216 | (9) | 1971 | (79) |  | |
Maternal education in years | <13 | 20198 | (31) | 244 | (150–515) |  | 3263 | (16) | 2886 | (14) | 14049 | (70) |  |
13 - 16 | 27606 | (42) | 338 | (172–567) | <0.0001 | 7118 | (26) | 5849 | (21) | 14639 | (53) | <0.0001 | |
>16 | 16838 | (26) | 374 | (187–581) |  | 5340 | (32) | 3916 | (23) | 7582 | (45) |  | |
Missing | 1372 | (2) | 283 | (161–550) |  | 302 | (22) | 226 | (17) | 844 | (62) |  | |
History of preterm delivery | No | 63698 | (97) | 314 | (168–559) | <0.0001 | 15510 | (24) | 12411 | (20) | 35777 | (56) | 0.047 |
Yes | 2205 | (3) | 276 | (158–539) |  | 487 | (22) | 435 | (20) | 1283 | (58) |  | |
Missing | 111 | (0.2) | 297 | (175–560) |  | 26 | (23) | 31 | (28) | 54 | (49) |  | |
History of abortion | No | 45164 | (68) | 315 | (168–559) | 0.15 | 10262 | (23) | 8930 | (20) | 25972 | (58) | <0.0001 |
Yes | 12418 | (19) | 308 | (166–558) |  | 3932 | (32) | 2296 | (19) | 6190 | (50) |  | |
 | Missing | 8432 | (13) | 308 | (165–557) |  | 1829 | (22) | 1651 | (20) | 4952 | (59) |  |
 | Never | 60452 | (92) | 322 | (170–563) |  | 15339 | (25) | 12271 | (20) | 32842 | (54) |  |
Smoking habits | Occasionally | 1741 | (3) | 261 | (158–511) | <0.0001 | 243 | (14) | 226 | (13) | 1272 | (73) | <0.0001 |
Daily | 3449 | (5) | 217 | (141–485) |  | 378 | (11) | 316 | (9) | 2755 | (80) |  | |
 | Missing | 372 | (0.6) | 236 | (148–500) |  | 63 | (17) | 64 | (17) | 245 | (66) |  |
Alcohol consumption in units/week | No alcohol | 58659 | (89) | 314 | (167–559) |  | 14448 | (25) | 11528 | (20) | 32683 | (56) |  |
<0.5 | 6155 | (9) | 311 | (170–556) | 0.21 | 1326 | (22) | 1164 | (19) | 3665 | (60) | <0.0001 | |
≥0.5 | 1200 | (2) | 286 | (167–531) |  | 249 | (21) | 185 | (15) | 766 | (64) |  | |
Partners with income of >300,000 | 0 | 18364 | (28) | 279 | (161–540) | <0.0001 | 3176 | (17) | 2904 | (16) | 12284 | (67) |  |
1 | 27212 | (41) | 309 | (166–557) | 6460 | (24) | 5451 | (20) | 15301 | (56) | <0.0001 | ||
2 | 18608 | (28) | 360 | (178–579) | 6130 | (33) | 4247 | (23) | 8231 | (44) |  | ||
NOK/year | Missing | 1830 | (3) | 264 | (158–533) |  | 257 | (14) | 275 | (15) | 1298 | (71) |  |
Baby's sex | Male | 33791 | (51) | 309 | (166–558) | 0.07 | 8190 | (24) | 6525 | (19) | 19076 | (57) | 0.4 |
Female | 32223 | (49) | 316 | (169–559) |  | 7833 | (24) | 6352 | (20) | 18038 | (56) |  | |
Tertiles of energy intake in MJ | 1 | 22005 | (33) | 272 | (127–525) |  | 5577 | (25) | 4338 | (20) | 12090 | (55) |  |
2 | 22005 | (33) | 317 | (166–561) | <0.0001 | 5511 | (25) | 4485 | (20) | 12009 | (55) | <0.0001 | |
3 | 22004 | (33) | 344 | (211–600) |  | 4935 | (22) | 4054 | (18) | 13015 | (59) |  |