The changes in female physical and childbearing characteristics in china and potential association with risk of breast cancer

Table 3 Changes in mean age at first birth, the frequency of miscarriage and mean age at menopause in women from Eastern China

age group	Age at first birth (years)			Times of miscarriage			Age at menopause
age group	number	mean ± SD	P value*	number	mean ± SD	P value*	number	mean ± SD	P value*
25-34	27226	22.38 ± 7.73		27164	0.29 ± 0.65
35-44	40832	24.36 ± 3.54		40777	0.42 ± 0.77
45-54	27092	24.39 ± 2.94	<0.001	27065	0.45 ± 0.83	<0.001	9955	47.92 ± 4.60
55-64	19641	23.95 ± 3.50		19626	0.27 ± 0.65		18118	49.28 ± 4.29	<0.001
65-70	7105	23.04 ± 4.00		7098	0.22 ± 0.61		6724	48.71 ± 4.62
total	121896	23.75 ± 4.80		121730	0.36 ± 0.74		34797	48.63 ± 4.82
loss value	162			328			1506

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