Ovulation patterns affect the offspring sex ratios and change with the women’s age

Table 1 Eight possible ovulation patterns in three consecutive menstrual cycles of infertile women, mean ages at conception and associated offspring sex ratios

Ovulation pattern	Mean age^#	No	Male/female*	Sex ratio	OR 95% CI	P-value
LLR	32.4 ± 4.2	97	69/28	2.464	1.00 control
RLR	31.7 ± 4.1	102	53/49	1.082	0.44 0.24–0.79	0.0059
LRR	33.5 ± 4.4	87	46/41	1.122	0.46 0.25–0.84	0.0145
RRR	33.2 ± 4.0	94	52/42	1.238	0.50 0.28–0.91	0.0253
RRL	32.3 ± 3.9	96	51/45	1.133	0.46 0.25–0.83	0.0117
LRL	33.6 ± 3.6	78	42/36	1.167	0.47 0.25–0.88	0.0267
RLL	31.9 ± 3.5	64	24/40	0.600	0.24 0.12–0.48	< 0.0001
LLL	34.9 ± 4.7^$	39	16/23	0.696	0.28 0.13–0.61	0.0016
Total	32.8 ± 4.1	657	353/304	1.161

R: right-sided ovulation; L: left-sided ovulation
^#ANOVA, P = 0.0002. ^$The mean age of LLL was significantly older than that of LLR, RLR, RRR, RRL or RLL (all P < 0.05). OR 95% CI: odds ratio 95% confidence intervals. *Heterogeneity χ² test: P = 0.0032

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