Relationships between the prenatal diagnosis rates for all
and types of BD and multiple pregnancies
The crude and adjusted relationships between the prenatal detection
rates for all and specific types of BD were summarized as odds ratios
and P -values. The 10 types of BD that showed significant crude or
adjusted associations are shown in Table 3. After adjustment for year of
birth, maternal age group, and maternal educational level, significantly
lower prenatal diagnosis rates for BDs associated with multiple births
remained for BDs as a whole (adjusted odds ratio
[ORadj ] = 0.36, 95% confidence interval
[CI]: 0.32–0.40, P <0.001), congenital heart
defects (ORadj = 0.32, 95% CI: 0.27–0.38,P <0.001), congenital hydrocephalus
(ORadj = 0.24, 95% CI: 0.13–0.45,P <0.001), cleft lip with cleft palate
(ORadj = 0.18, 95% CI: 0.11–0.30,P <0.001), congenital talipes equinovarus
(ORadj = 0.50, 95% CI: 0.27–0.92,P =0.025), cleft lip without cleft palate
(ORadj = 0.27, 95% CI: 0.14–0.50,P <0.001), limb reduction defects
(ORadj , = 0.33 95% CI: 0.16–0.68,P =0.003), congenital diaphragmatic hernia
(ORadj = 0.18, 95% CI: 0.06–0.58,P =0.004), trisomy 21 syndrome (ORadj =
0.09, 95% CI: 0.04–0.23, P <0.001), congenital
malformation of the urinary system (ORadj = 0.30,
95% CI: 0.19–0.47, P <0.001), and other chromosomal
malformation (ORadj = 0.22, 95% CI: 0.06–0.86,P =0.030).