Table 3

RR of CHD according to maternal age and year of delivery

Maternal age at delivery*N, Unadjusted RR (95% CI)
Twins (any chorionicity)Dichorionic twinsMonochorionic twinsSingletons*
<20N=14
RR=1.93 (0.96 to 3.88)
N=5
RR=1.06 (0.33 to 3.44)
N=8
RR=3.37 (1.27 to 8.95)
N=290
RR=0.94 (0.83 to 1.07)
20–29N=66
RR=1 (reference)
N=40
RR=1 (reference)
N=21
RR=1 (reference)
N=1491
RR=1 (reference)
30–34N=40
RR=0.74 (0.50 to 1.10)
N=25
RR=0.76 (0.46 to 1.26)
N=11
RR=0.64 (0.31 to 1.33)
N=754
RR=1.04 (0.95 to 1.13)
≥35N=34
RR=0.97 (0.64 to 1.47)
N=26
RR=1.22 (0.75 to 2.01)
N=7
RR=0.63 (0.27 to 1.48)
N=422
RR=1.03 (0.93 to 1.15)
Year of deliveryRR=1.00 (0.96 to 1.04)RR=0.96 (0.91 to 1.02)RR=1.08 (1.01 to 1.18)RR=0.98 (0.97 to 0.99)
  • *Twenty-nine (0.7%) singletons had missing maternal age data and were excluded. Maternal age data were missing in 2.1% of twins without CHD so these were excluded from the denominator.

  • CHD, congenital heart disease; RR, relative risk.