Table 2.

Male-to-female ratios at birth and relative risk for male birth in Victoria 1999–2015 by mother’s birthplace, stratified by birth plurality

Mother’s country of birth	n males/n females	M/F ratio	RRa(95% CI)	Sig.
Singleton and multiple births
All births	611 078/579 548	1.054 (1.051–1.058)	–
Australia	436 724/414 874	1.053 (1.048–1.057)	Ref.
India	18 887/17 508	1.079 (1.057–1.101)	1.012 (1.001–1.022)	0.025
UK	14 962/14 199	1.054 (1.030–1.078)	1.001 (0.990–1.013)	0.801
Vietnam	14 311/13 599	1.052 (1.028–1.077)	1.000 (0.988–1.012)	0.999
China	12 225/11 217	1.090 (1.062–1.118)	1.017 (1.005–1.030)	0.007
New Zealand	11 883/11 123	1.068 (1.041–1.096)	1.007 (0.994–1.020)	0.273
Philippines	5678/5518	1.029 (0.992–1.068)	0.989 (0.971–1.008)	0.247
Sri Lanka	5728/5462	1.049 (1.011–1.088)	0.998 (0.980–1.017)	0.864
Rest of European Region	22 397/21 219	1.056 (1.036–1.076)	1.002 (0.992–1.011)	0.726
Eastern Mediterranean Region	19 847/18 803	1.056 (1.035–1.077)	1.001 (0.991–1.011)	0.888
Rest of Western Pacific Region	18 456/17 614	1.048 (1.026–1.070)	0.998 (0.988–1.009)	0.741
African Region	9693/9261	1.047 (1.017–1.077)	0.997 (0.983–1.011)	0.688
Rest of South East Asia Region	8465/7825	1.082 (1.049–1.116)	1.013 (0.998–1.028)	0.086
Region of the Americas	7516/7190	1.045 (1.012–1.080)	0.997 (0.982–1.013)	0.751
Singleton births
Australia	421 386/400 092	1.053 (1.049–1.058)	Ref.
India	18 408/17 111	1.076 (1.054–1.098)	1.010 (1.000–1.020)	0.055
UK	14 391/13 674	1.052 (1.028–1.077)	1.001 (0.989–1.012)	0.923
Vietnam	14 052/13 315	1.055 (1.031–1.081)	1.001 (0.989–1.012)	0.851
China	11 992/10 986	1.092 (1.064–1.120)	1.018 (1.005–1.031)	0.006
New Zealand	11 521/10 733	1.073 (1.046–1.102)	1.009 (0.996–1.022)	0.164
Philippines	5554/5388	1.031 (0.993–1.070)	0.990 (0.972–1.008)	0.280
Sri Lanka	5563/5315	1.047 (1.008–1.087)	0.997 (0.979–1.016)	0.765
Rest of European Region	21 680/20 493	1.058 (1.038–1.078)	1.003 (0.993–1.012)	0.605
Eastern Mediterranean Region	19 278/18 291	1.054 (1.033–1.076)	1.000 (0.990–1.010)	0.962
Rest of Western Pacific Region	17 990/17 191	1.046 (1.025–1.069)	0.997 (0.987–1.008)	0.622
African Region	9375/8975	1.045 (1.015–1.075)	0.996 (0.982–1.010)	0.572
Rest of South East Asia Region	8296/7657	1.083 (1.050–1.118)	1.014 (0.998–1.029)	0.078
Region of the Americas	7286/6975	1.045 (1.011–1.079)	0.997 (0.981–1.013)	0.697
Multiple births
Australia	15 332/14 782	1.037 (1.014–1.061)	Ref.
India	478/397	1.204 (1.054–1.375)	1.072 (1.008–1.140)	0.026
UK	571/525	1.088 (0.966–1.224)	1.024 (0.967–1.086)	0.415
Vietnam	259/284	0.912 (0.771–1.079)	0.937 (0.857–1.024)	0.150
China	233/231	1.009 (0.841–1.210)	0.987 (0.900–1.081)	0.771
New Zealand	362/390	0.928 (0.805–1.071)	0.945 (0.877–1.019)	0.143
Philippines	124/130	0.954 (0.746–1.219)	0.959 (0.845–1.088)	0.514
Sri Lanka	165/147	1.122 (0.899–1.401)	1.040 (0.936–1.155)	0.471
Rest of European Region	715/726	0.985 (0.888–1.092)	0.975 (0.925–1.028)	0.354
Eastern Mediterranean Region	569/512	1.111 (0.986–1.252)	1.033 (0.975–1.095)	0.266
Rest of Western Pacific Region	466/423	1.102 (0.966–1.257)	1.030 (0.967–1.098)	0.360
African Region	318/286	1.112 (0.948–1.304)	1.034 (0.958–1.117)	0.386
Rest of South East Asia Region	169/168	1.006 (0.813–1.245)	0.985 (0.885–1.096)	0.783
Region of the Americas	230/215	1.070 (0.888–1.288)	1.016 (0.928–1.113)	0.727

Bold: M/F ratio point estimate above or below 1.04–1.06 with a 95% CI excluding the natural ratio of 1.05, or RR with P = <0.05.

Sig., significance; M/F ratio, male-to-female ratio. RR, relative risk.

^aAdjusted for maternal age.