Table 4.
Male-to-female ratios by mother’s birthplace and relative risk for male birth, stratified by time period and parity
| Mother’s country of birth | Time period | Parity | n males/n females | M/F ratio | RRa (95% CI) | Sig. |
|---|---|---|---|---|---|---|
| Australia | 1999–2004 | All | 147 040/140 189 | 1·049 (1·041–1·057) | Ref.b | |
| 0 | 62 620/59 635 | 1·050 (1·038–1·062) | Ref. | |||
| 1 | 50 960/48 820 | 1·044 (1·031–1·057) | Ref. | |||
| ≥2 | 33 459/31 734 | 1·054 (1·038–1·071) | Ref. | |||
| 2005–10 | All | 159 217/151 215 | 1·053 (1·046–1·060) | Ref. | ||
| 0 | 68 410/64 370 | 1·063 (1·051–1·074) | Ref. | |||
| 1 | 55 211/52 600 | 1·050 (1·037–1·062) | Ref. | |||
| ≥2 | 35 580/34 229 | 1·039 (1·024–1·055) | Ref. | |||
| 2011–15 | All | 130 467/123 470 | 1·057 (1·048–1·065) | Ref. | ||
| 0 | 56 965/53 683 | 1·061 (1·049–1·074) | Ref. | |||
| 1 | 45 890/43 376 | 1·058 (1·044–1·072) | Ref. | |||
| ≥2 | 27 600/26 401 | 1·045 (1·028–1·063) | Ref. | |||
| India | 1999–2004 | All | 1701/1646 | 1·033 (0·966–1·106) | 0·993 (0·960–1·027) | 0·673 |
| 0 | 779/779 | 1·000 (0·905–1·104) | 0·976 (0·929–1·026) | 0·346 | ||
| 1 | 715/657 | 1·088 (0·979–1·210) | 1·020 (0·969–1·073) | 0·450 | ||
| ≥2 | 207/210 | 0·986 (0·814–1·194) | 0·969 (0·879–1·068) | 0·522 | ||
| 2005–10 | All | 5984/5451 | 1·098 (1·058–1·139) | 1·019 (1·001–1·037) | 0·039 | |
| 0 | 3841/3451 | 1·113 (1·063–1·165) | 1·021 (0·999–1·045) | 0·064 | ||
| 1 | 1753/1636 | 1·072 (1·002–1·146) | 1·010 (0·977–1·044) | 0·558 | ||
| ≥2 | 389/364 | 1·069 (0·926–1·233) | 1·016 (0·947–1·089) | 0·663 | ||
| 2011–15 | All | 11 202/10 411 | 1·076 (1·048–1·105) | 1·009 (0·995–1·022) | 0·207 | |
| 0 | 6508/6279 | 1·036 (1·001–1·073) | 0·988 (0·971–1·006) | 0·201 | ||
| 1 | 4049/3602 | 1·124 (1·075–1·176) | 1·029 (1·007–1·052) | 0·010 | ||
| ≥2 | 643/528 | 1·218 (1·085–1·366) | 1·074 (1·019–1·132) | 0·008 | ||
| China | 1999–2004 | All | 2428/2221 | 1·093 (1·032–1·158) | 1·020 (0·993–1·049) | 0·153 |
| 0 | 1085/985 | 1·102 (1·011–1·201) | 1·024 (0·983–1·068) | 0·260 | ||
| 1 | 1065/980 | 1·087 (0·996–1·185) | 1·018 (0·976–1·062) | 0·412 | ||
| ≥2 | 278/256 | 1·086 (0·917–1·287) | 1·017 (0·937–1·104) | 0·689 | ||
| 2005–10 | All | 3388/3051 | 1·110 (1·057–1·166) | 1·027 (1·003–1·051) | 0·029 | |
| 0 | 1972/1788 | 1·103 (1·035–1·176) | 1·018 (0·988–1·050) | 0·245 | ||
| 1 | 1193/1052 | 1·134 (1·044–1·232) | 1·038 (0·998–1·080) | 0·061 | ||
| ≥2 | 223/221 | 1·057 (0·876–1·275) | 1·011 (0·923–1·109) | 0·810 | ||
| 2011–15 | All | 6409/5945 | 1·078 (1·041–1·117) | 1·010 (0·922–1·027) | 0·286 | |
| 0 | 3739/3561 | 1·050 (1·003–1·099) | 0·995 (0·972–1·018) | 0·657 | ||
| 1 | 2287/2077 | 1·101 (1·038–1·168) | 1·019 (0·990–1·049) | 0·196 | ||
| ≥2 | 383/307 | 1·248 (1·074–1·449) | 1·084 (1·014–1·160) | 0·018 | ||
| Rest of South East | 1999–2004 | All | 1448/1353 | 1·070 (0·994–1·153) | 1·010 (0·974–1·047) | 0·595 |
| Asia region | 0 | 749/659 | 1·137 (1·024–1·262) | 1·038 (0·989–1·091) | 0·134 | |
| 1 | 445/431 | 1·032 (0·904–1·179) | 0·995 (0·932–1·062) | 0·870 | ||
| ≥2 | 254/263 | 0·966 (0·813–1·147) | 0·958 (0·877–1·046) | 0·335 | ||
| 2005–10 | All | 2919/2600 | 1·123 (1·065–1·183) | 1·031 (1·005–1·057) | 0·018 | |
| 0 | 1404/1292 | 1·087 (1·008–1·172) | 1·010 (0·974–1·048) | 0·576 | ||
| 1 | 990/840 | 1·179 (1·075–1·292) | 1·056 (1·012–1·102) | 0·012 | ||
| ≥2 | 525/467 | 1·124 (0·993–1·273) | 1·038 (0·979–1·102) | 0·213 | ||
| 2011–15 | All | 4098/3872 | 1·058 (1·013–1·106) | 1·000 (0·979–1·022) | 0·969 | |
| 0 | 1950/1871 | 1·042 (0·978–1·110) | 0·991 (0·960–1·022) | 0·560 | ||
| 1 | 1394/1338 | 1·042 (0·967–1·123) | 0·992 (0·956–1·030) | 0·692 | ||
| ≥2 | 752/661 | 1·138 (1·025–1·263) | 1·041 (0·991–1·094) | 0·109 |
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.
a
Adjusted for maternal age.
b
Individual Australian-born year and parity group used as reference (Ref.) for the corresponding year and parity group from each of the other countries/regions.