Table 3.

Distribution of MTHFR 677C>T genotype and allele frequencies as a function of age and health status during pregnancy among different age groups from Yunnan.

		Genotypes
		CC		CT		TT		Allele frequency
Age at pregnancy	Health status during pregnancy	n	%	n	%	n	%	C	T	P∗
<30 yr n = 1879	Unhealthy pregnancy	29	27.1	48	44.9	30	28.0	49.5	50.5	.000
	Healthy pregnancy	718	40.5	800	45.2	254	14.3	63.1	36.9
30–40 yr n = 1402	Unhealthy pregnancy	31	26.7	66	56.9	19	16.4	55.2	44.8	.015
	Healthy pregnancy	523	40.7	581	45.2	182	14.2	63.3	36.7
>40 yr n = 106	Unhealthy pregnancy	8	38.1	11	52.3	2	9.5	64.3	35.7	.625
	Healthy pregnancy	41	48.2	34	40.0	10	11.8	68.2	31.8