Comparison of Naturally Conceived and IVF-DZ Twins in the Netherlands Twin Registry: A Developmental Study
Table 1
Parental, birth, and child characteristics of IVF/ICSI DZ twin pairs, naturally conceived (NC) DZ twin pairs, and a group of DZ twin pairs matched for birth cohort, educational level, maternal age, gestational age, and smoking behavior during pregnancy (matched NC pairs).
NC pairs
IVF/ICSI pairs
*
Matched NC pairs
**
Age mother (y) (mean ± SD)
30.99 (3.78)
33.25 (3.44)
<0.001
33.08 (3.68)
0.185
Age father (y) (mean ± SD)
33.19 (2.44)
36.03 (4.68)
<0.001
35.01 (4.69)
0.001
Smoked during pregnancy (% yes)
1344 (25.3%)
264 (17.2%)
<0.001
283 (18.8%)
0.249
Educational level
% Low
1999 (37.6%)
553 (36.0%)
0.515
544 (36.2%)
0.842
% Middle
2184 (41.1%)
651 (42.4%)
649 (43.2%)
% High
1132 (21.2%)
330 (21.5%)
311 (20.7%)
Gestational age (weeks) (mean ± SD)
36.84 (2.43)
36.40 (2.54)
<0.001
36.50 (2.43)
0.241
% >32 and <37 weeks
1539 (29.0%)
561 (36.6%)
<0.001
551 (36.6%)
0.847
% ≤32 weeks
326 (6.1%)
109 (7.1%)
99 (6.6%)
Child sex (% boys)
5464 (51.4%)
1586 (51.7%)
0.775
1566 (52.1%)
0.775
Older sibs (%)
2199 (57.2%)
232 (21.5%)
<0.001
691 (63.3%)
<0.001
Height mother (cm) (mean ± SD)
170.39 (6.42)
169.91 (6.67)
0.012
170.49 (6.45)
0.017
Weight before pregnancy (kg) (mean ± SD)
69.13 (11.77)
68.52 (11.69)
0.077
69.40 (11.95)
0.042
Weight gain during pregnancy (kg) (mean ± SD)
16.41 (6.23)
16.35 (6.54)
0.782
16.24 (6.04)
0.630
Note: * value based on tests comparing IVF and unmatched NC twin pairs ** value based on tests comparing IVF and matched NC twin pairs.
