Table 4. IR and risk of any cancer before 18 years of age in children conceived by FET, fresh embryo transfer, or spontaneous conception and born in Denmark, Norway, or Swedena (Denmark 1994–2014, Norway 1984–2015, and Sweden 1985–2015).
| FET Children All N = 22,630b Singletons N = 18,872 Multiples N = 3,758 Person-years All N = 159,566 Singletons N = 124,839 Multiples N = 34,728 |
Fresh embryo transfer Children All N = 115,474 Singletons N = 83,623 Multiples N = 31,851 Person-years All N = 1,207,598 Singletons N = 804,450 Multiples N = 401,148 |
Spontaneous conception Children All N = 6,306,023 Singletons N = 6,142,874 Multiples N = 163,149 Person-years All N = 79,920,380 Singletons N = 77,896,756 Multiples N = 2,023,624 |
FET vs. fresh embryo transfer | FET vs. spontaneous conception | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. of children with cancer | IR | No. of children with cancer | IR | No. of children with cancer | IR | HR (95% CI) p-value | aHR (95% CI) p-value | aHR (95% CI) p-value | aHR (95% CI) p-value | HR (95% CI) p-value | aHR (95% CI) p-value | aHR (95% CI) p-value | aHR (95% CI) p-value | ||||
| Per 1,000 children | Per 100,000 person-years | Per 1,000 children | Per 100,000 person-years | Per 1,000 children | Per 100,000 person-years | ||||||||||||
| All | 48 | 2.12 | 30.08 | 227 | 1.97 | 18.80 | 13,044 | 2.07 | 16.32 | 1.51 (1.11 to 2.07) 0.01 |
1.59c (1.15 to 2.20) 0.005 |
1.54d (1.11 to 2.14) 0.009 1.55e (1.12 to 2.15) 0.09 |
1.59f (1.15 to 2.20) 0.005 1.63g (1.17 to 2.26) 0.003 |
1.69 (1.27 to 2.24) <0.001 |
1.65c (1.24 to 2.19) 0.001 |
1.65d (1.24 to 2.19) 0.001 1.62e (1.22 to 2.17) 0.001 |
1.87f (1.73 to 2.02) <0.001 |
| Singletons | 35 | 1.85 | 28.04 | 146 | 1.75 | 18.15 | 12,734 | 2.07 | 16.35 | 1.45 (1.0003 to 3.24) 0.05 |
1.49h (1.01 to 2.18) 0.04 |
1.42i (0.96 to 2.09) 0.08 1.47j (1.00 to 2.16) 0.049 |
1.49k (1.01 to 2.18) 0.04 1.51l (1.03 to 2.23) 0.04 |
1.55 (1.11 to 2.16) 0.01 |
1.49h (1.07 to 2.08) 0.01 |
1.49i (1.07 to 2.08) 0.02 1.49 j (1.07 to 2.08) 0.02 |
1.49k (1.06 to 2.07) 0.02 |
| Multiples | 13 | 3.46 | 37.43 | 81 | 2.54 | 20.19 | 310 | 1.90 | 15.32 | 1.80 (1.001 to 3.24) 0.05 |
1.91h 1.04 to 3.50) 0.04 |
1.94i (1.06 to 3.54) 0.03 1.93 j (1.06 to 3.54) 0.03 |
1.91k (1.04 to 3.50) 0.04 2.00l (1.09 to 3.65) 0.03 |
2.32 (1.33 to 4.05) 0.01 |
2.34h (1.33 to 4.12) 0.01 |
2.37i (1.34 to 4.18) 0.01 2.36 j (1.34 to 4.16) 0.003 |
2.34k (1.33 to 4.12) 0.01 |
aWithout data from Finland because no information about frozen or fresh embryo transfer available in Finland.
bThere were missing data on frozen or fresh embryo transfer in the ART group in 3,988/142,092 (2.8%).
cAdjusted for sex, plurality, year of birth, country of birth, maternal age at birth, and parity.
dAdjusted for sex, plurality, year of birth, country of birth, maternal age at birth, parity, and macrosomia (≥4,000 g).
eAdjusted for sex, plurality, year of birth, country of birth, maternal age at birth, parity, and birth weight (continuous variable).
fAdjusted for sex, plurality, year of birth, country of birth, maternal age at birth, parity, and major birth defects [36].
gAdjusted for sex, plurality, year of birth, country of birth, maternal age at birth, parity, and embryo stage.
hAdjusted for sex, year of birth, country of birth, maternal age at birth, and parity.
iAdjusted for sex, year of birth, country of birth, maternal age at birth, parity, and macrosomia (≥4,000 g).
jAdjusted for sex, year of birth, country of birth, maternal age at birth, and birth weight (continuous variable).
kAdjusted for sex, year of birth, country of birth, maternal age at birth, parity, and major birth defects [36].
lAdjusted for sex, year of birth, country of birth, maternal age at birth, parity, and embryo stage.
aHR, adjusted hazard ratio; ART, assisted reproduction technology; CI, confidence interval; FET, frozen-thawed embryo transfer; HR, hazard ratio; IR, incidence rate.