Table 1. Characteristics of study population by mode of conception defined as ART or SC and by country of birth in children born in Denmark 1994–2014, Finland 1990–2014, Norway 1984–2015, or Sweden 1985–2015.
| All countries N = 7,944,248 | Denmark N = 1,355,267 | Finland N = 1,496,133 | Norway N = 1,865,484 | Sweden N = 3,227,364 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| ART N = 171,774 | SC N = 7,772,474 | ART N = 45,783 | SC N = 1 309,484 | ART N = 29,682 | SC N = 1,466,451 | ART N = 34,042 | SC N = 1,831,442 | ART N = 62,267 | SC N = 3,165,097 | |
| Child characteristics | ||||||||||
| Calendar year of birth, N (%) | ||||||||||
| 1984–1990 | 1,676 (1.0) |
1,095,853 (14.1) |
- | - | 53 (0.2) |
65,203 (4.5) |
877 (2.6) |
383,757 (21.0) |
746 (1.2) |
646,893 (20.4) |
| 1991–1995 | 11,681 (6.8) |
1,321,054 (17.0) |
1,299 (2.8) |
138,138 (10.6) |
2,864 (9.7) |
320,916 (21.9) |
2,464 (7.2) |
297,356 (16.2) |
5,054 (8.1) |
564,644 (17.8) |
| 1996–2000 | 28,705 (16.7) |
1,133,572 (17.2) |
8,532 (18.6) |
327,305 (25.0) |
6,937 (23.4) |
283,142 (19.3) |
4,313 (12.7) |
292,015 (15.9) |
8,923 (14.3) |
431,110 (13.6) |
| 2001–2005 | 36,089 (21.0) |
1,332,301 (17.1) |
11,797 (25.8) |
313,095 (23.9) |
6,357 (21.4) |
276,286 (18.8) |
6,586 (19.4) |
276,926 (15.1) |
11,349 (18.2) |
465,994 (14.7) |
| 2006–2010 | 45,499 (26.5) |
1,414,136 (18.2) |
13,139 (28.7) |
310,160 (23.7) |
6,971 (23.5) |
291,843 (19.9) |
9,411 (27.7) |
293,014 (16.0) |
15,978 (25.7) |
519,119 (16.4) |
| 2011–2015 | 48,124 (28.0) |
1,275,558 (16.4) |
11,016 (24.1) |
220,786 (16.9) |
6,500 (21.9) |
229,061 (15.6) |
10,391 (30.5) |
288,374 (15.8) |
20,217 (32.5) |
537,337 (17.0) |
| Birth weight, N (%) | ||||||||||
| Very low birth weight, <1,500 g | 5,220 (3.1) |
56,245 (0.7) |
1,566 (3.5) |
10,331 (0.8) |
844 (2.8) |
9,494 (0.7) |
1,233 (3.6) |
14,584 (0.8) |
1,577 (2.5) |
21,836 (0.7) |
| Low birth weight, <2,500 g | 22,241 (13.0) |
272,089 (3.5) |
6,894 (15.2) |
50,901 (4.0) |
3,936 (13.3) |
46,765 (3.2) |
4,870 (14.3) |
67,004 (3.7) |
6,541 (10.6) |
107,419 (3.4) |
| Macrosomia, ≥4,000 g | 20,522 (12.0) |
1,458,901 (18.9) |
4,723 (10.4) |
238,105 (18.5) |
3,521 (11.9) |
272,308 (18.6) |
3,933 (11.6) |
355,748 (19.4) |
8,345 (13.5) |
592,740 (18.8) |
| Birth weight, g, mean (SD) | 3,193 (754) |
3,517 (584) |
3,109 (764) |
3,492 (596) |
3,200 (745) |
3,527 (566) |
3,155 (780) |
3,522 (595) |
3,272 (729) |
3,520 (582) |
| Missing data for birth weight, N (%) | 755 (0.4) |
36,522 (0.5) |
463 (1.0) |
24,570 (1.9) |
13 (0.04) |
3,405 (0.2) |
35 (0.1) |
1,556 (0.1) |
244 (0.4) |
6,991 (0.2) |
| Gestational age, N (%) | ||||||||||
| Extremely preterm birth, <28+0 weeks | 2,100 (1.2) |
22,136 (0.3) |
677 (1.5) |
4,075 (0.3) |
341 (1.2) |
3,800 (0.3) |
476 (1.4) |
5,627 (0.3) |
606 (1.0) |
8,634 (0.3) |
| Very preterm birth, <32+0 weeks | 4,364 (2.6) |
47,876 (0.6) |
1,334 (2.9) |
9,355 (0.7) |
681 (2.3) |
7,616 (0.5) |
978 (2.9) |
12,110 (0.7) |
1,371 (2.2) |
18,795 (0.6) |
| Preterm birth, <37+0 weeks | 27,462 (16.1) |
428,385 (5.6) |
8,364 (18.4) |
82,501 (6.4) |
5,125 (17.3) |
74,474 (5.1) |
5,842 (17.3) |
99,294 (5.7) |
8,131 (13.1) |
172,116 (5.5) |
| Postterm birth, ≥42+0 weeks | 5,057 (3.0) |
374,569 (4.9) |
789 (1.7) |
40,354 (3.1) |
573 (1.9) |
40,738 (2.8) |
1,152 (3.4) |
124,498 (7.2) |
2,543 (4.1) |
168,979 (5.4) |
| Gestational age, days, mean (SD) | 270 (20) |
278 (14) |
268 (21) |
278 (14) |
270 (20) |
278 (13) |
270 (21) |
279 (14) |
273 (19) |
278 (13) |
| Missing data for gestational age, N (%) | 652 (0.4) |
129,426 (1.7) |
298 (0.7) |
28,949 (2.2) |
57 (0.2) |
6,738 (0.5) |
246 (0.7) |
89,599 (4.9) |
51 (0.1) |
4,140 (0.1) |
| Plurality, N (%) | ||||||||||
| Singletons | 127,230 (74.1) |
7,573,456 (97.4) |
30,997 (67.7) |
1,269,481 (97.0) |
22,038 (74.3) |
1,430,582 (97.6) |
24,114 (70.1) |
1,783,892 (97.4) |
50,081 (80.4) |
3,089,501 (97.6) |
| Twins | 42,536 (24.8) |
194,464 (2.5) |
14,392 (31.4) |
38,981 (3.0) |
7,196 (24.2) |
35,165 (2.4) |
9,367 (27.5) |
46,389 (2.5) |
11,581 (18.6) |
73,929 (2.3) |
| Triplets and higher order multiples | 2,008 (1,2) |
4,554 (0.1) |
394 (0.9) |
1,022 (0.1) |
448 (1.5) |
704 (0.1) |
561 (1.7) |
1,161 (0.1) |
605 (1.0) |
1,667 (0.1) |
| Birth defects, N (%) | ||||||||||
| Any major defectsa (non-chromosomal or chromosomal defects) | 8,965 (5.2) |
263,781 (3.4) |
2,597 (5.6) |
48,686 (3.7) |
2,165 (7.3) |
67,234 (4.6) |
1,802 (5.3) |
62,089 (3.4) |
2,401 (3.8) |
85,772 (2.7) |
| Major birth defectsa (non-chromosomal) | 8,679 (5.1) |
256,525 (3.3) |
2,536 (5.5) |
47,388 (3.6) |
2,099 (7.1) |
65,291 (4.5) |
1,733 (5.1) |
60,506 (3.3) |
2,311 (3.7) |
83,340 (2.6) |
| Chromosomal defects (with or without other major birth defectsa) | 286 (0.17) |
7,256 (0.09) |
61 (0.13) |
1,298 (0.10) |
66 (0.22) |
1,943 (0.13) |
69 (0.20) |
1,583 (0.09) |
90 (0.14) |
2,432 (0.08) |
| Male sex, N (%) | 87,805 (51.1) |
3,988,987 (51.3) |
23,202 (50.7) |
672,088 (51.3) |
15,192 (51.2) |
749,359 (51.1) |
17,456 (51.3) |
940,571 (51.4) |
31,955 (51.3) |
1,626,969 (51.4) |
| Age at cancer diagnosis (year), mean (SD), median (range) | 6.0 (5.0) 4.3 (0–18) |
6.8 (5.4) 5.2 (0–18) |
7.0 (5.3) 5.2 (0–17) |
6.9 (5.4) 5.3 (0–18) |
5.9 (4.8) 4.7 (0–17) |
6.6 (5.3) 4.8 (0–18) |
5.4 (4.8) 4.1 (0–18) |
7.3 (5.6) 5.7 (0–18) |
5.2 (4.5) 3.5 (0–17) |
6.7 (5.3) 5.0 (0–18) |
| Follow-up time (year), mean (SD), median (range) | 9.9 (5.8) 9.5 (0–18) |
12.5 (5.9) 14.5 (0–18) |
12.0 (4.8) 12.2 (0–18) |
13.2 (4.9) 14.4 (0–18) |
10.0 (5.9) 10.1 (0–18) |
11.7 (6.0) 12.8 (0–18) |
9.0 (5.8) 8.2 (0–18) |
12.8 (6.0) 15.7 (0–18) |
8.9 (5.9) 7.9 (0–18) |
12.4 (6.2) 15.0 (0–18) |
| Maternal characteristics | ||||||||||
| Age at delivery, (year), mean (SD) | 33.9 (4.2) |
29.7 (5.2) |
33.6 (4.1) |
30.2 (4.9) |
33.9 (4.6) |
29.8 (5.3) |
33.6 (4.1) |
29.3 (5.2) |
34.2 (4.1) |
29.8 (5.2) |
| Primiparous, N (%) | 116,551 (68.1) |
3,244,158 (41.8) |
30,479 (67.4) |
554,294 (42.9) |
20,132 (67.9) |
592,796 (40.5) |
21,733 (63.8) |
756,578 (41.3) |
44,207 (71.0) |
1,340,490 (42.4) |
| Smoking during pregnancyb, N (%) | 10,141 (6.4) |
989,017 (15.1) |
3,956 (9.3) |
194,512 (16.5) |
1,820 (6.2) |
224,725 (15.7) |
1,735 (6.1) |
129,171 (13.4) |
2,630 (4.5) |
440,609 (14.7) |
| Missing data for smoking, N (%) | 12,944 (7.5) |
1,213,569 (15.6) |
3,217 (7.0) |
132,470 (10.1) |
447 (1.5) |
37,222 (2.5) |
5,703 (16.8) |
868,891 (47.4) |
3,577 (5.7) |
174,986 (5.5) |
| BMI (kg/m2), mean (SD) | 24.3 (4.1) |
24.2 (4.5) |
24.0 (4.3) |
24.3 (5.0) |
24.1 (4.3) |
24.3 (4.8) |
24.4 (4.4) |
24.3 (4.8) |
24.4 (3.9) |
24.1 (4.3) |
| Missing data for BMI, N (%) | 64,265 (37.4) |
3,814,698 (49.1) |
17,836 (40.0) |
693,037 (52.9) |
14,610 (49.2) |
866,154 (59.1) |
24,402 (71.7) |
1,575,159 (86.0) |
7,417 (11.9) |
680,348 (21.5) |
| Educational level, N (%)c, d | ||||||||||
| Low (ISCED <5) | 59,198 (44.7) |
3,103,182 (56.1) |
24,091 (53.3) |
775,825 (61.0) |
8,674 (30.9) |
604,310 (46.2) |
NA | NA | 26,433 (44.7) |
1,723,047 (58.3) |
| Medium (ISCED 5–6) | 45,322 (34.2) |
1,651,780 (29.8) |
13,657 (30.1) |
342,858 (26.9) |
11,349 (40.4) |
466,435 (35.7) |
NA | NA | 20,316 (34.3) |
842,487 (28.5) |
| High (ISCED 7–8) | 27,952 (21.1) |
781,679 (14.1) |
7,455 (16.5) |
154,279 (12.1) |
8,078 (28.8) |
237,128 (18.1) |
NA | NA | 12,419 (20.1) |
390,272 (13.2) |
| Missing data for educational level | 5,260 (4.0) |
404,391 (7.3) |
580 (1.3) |
36,522 (2.8) |
1,581 (5.3) |
158,578 (10.8) |
NA | NA | 3,099 (5.0) |
209,291 (6.6) |
| Assisted reproduction methode, N (%) | ||||||||||
| IVF | 81,948 (57.7) |
- | 25,006 (54.6) |
- | NA | - | 20,093 (59.0) |
- | 36,849 (59.2) |
- |
| ICSI | 55,126 (38.8) |
- | 18,118 (39.6) |
- | NA | - | 11,590 (34.0) |
- | 25,418 (40.8) |
- |
| Missing data for IVF/ICSI | 5,018 (3.5) |
- | 2,659 (5.8) |
- | NA | - | 2,359 (7.0) |
- | 0 | - |
| Fresh embryo transfer | 115,474 (81.3) |
- | 41,022 (89.6) |
- | NA | - | 25,630 (75.3) |
- | 48,822 (78.4) |
- |
| Frozen embryo transfer | 22,630 (15.9) |
- | 4,761 (10.4) |
- | NA | - | 4,424 (13.0) |
- | 13,445 (21.6) |
- |
| Missing data for fresh/frozen embryo transfer | 3,988 (2.8) |
- | 0 | - | NA | - | 3,988 (11.7) |
- | 0 | - |
| Cleavage stage embryo | 130,784 (92.0) |
- | 42,444 (92.7) |
- | NA | - | 33,628 (98.8) | - | 54,712 (87.9) |
- |
| Blastocysts | 9,623 (6.8) |
1,654 (3.6) |
414 (1.2) |
7,555 (12.1) |
||||||
| Missing data for embryo stage | 1,685 (1.2) |
- | 1,685 (3.7) |
- | NA | - | 0 | - | 0 | - |
| Autologous oocytes | 140,682 (99.0) |
- | 45,073 (98.4) |
- | NA | - | 34,042 (100) |
- | 61,567 (98.9) |
|
| Donated oocytes | 1,410 (1.0) |
- | 710 (1.6) |
NA | - | 0f | - | 700 (1.1) |
- | |
aMajor birth defects defined according to the EUROCAT classification system [37].
bData for Denmark, Finland, and Sweden but only birth cohorts since 1999 from Norway when smoking habits were first registered.
cData for Denmark, Finland, and Sweden because no data were available for Norway.
dEducational level according to International Standard Classification of Education (ISCED2011), ISCED <5 = primary, secondary, or post-secondary non tertiary education, ISCED 5–6 = first stage of tertiary education (bachelors or equivalent), ISCED 7–8 = second stage of tertiary education (master, doctorate, or more) [44].
eData for Denmark, Norway, and Sweden because no data on assisted reproductive method were available for Finland.
fOocyte donation not permitted in Norway.
ART, assisted reproductive technology; BMI, body mass index; ICSI, intracytoplasmic sperm injection; ISCED, international standard classification of education; IVF, in vitro fertilization; LGA, large for gestational age; NA, not available; SC, spontaneous conception; SGA, small for gestational age.