Table 2.

Trends in the incidence of chromosomal abnormalities among all mothers and mothers aged 35 years and older over time

Time	General population			Mothers over 35 years population			RR (95% CI)
	No. of births	No. of abnormal cases	Per 10,000 births	No. of births	No. of abnormal cases	Per 10,000 births
2011	221,469	89	4.02	19,557	30	15.34	3.82(2.53 ~ 5.78)
2012	253,540	136	5.36	22,397	37	16.52	3.08(2.14 ~ 4.44)
2013	266,036	164	6.16	29,309	63	27.47	4.47(3.34 ~ 5.97)
2014	265,289	181	6.82	23,635	67	28.35	4.16(3.15 ~ 5.51)
2015	264,017	241	9.13	26,608	90	33.82	3.72(2.92 ~ 4.73)
Total	1,270,351	811	6.38	115,127	287	24.93	3.91(3.42 ~ 4.48)