The reasoning: the fertility ladder
| Measure | Formula | Comment |
|---|---|---|
| CBR | Live births/mid‑year population × 1,000 | Crude; affected by age–sex structure |
| GFR | Live births/women 15–44 (or 15–49) × 1,000 | Better denominator |
| GMFR (general marital fertility rate) | Legitimate live births/married women 15–49 × 1,000 | |
| ASFR | Births to women in age group/women in that group × 1,000 | Peak in India at 20–24 (shifting to 25–29) |
| TFR | 5 × ΣASFR/1,000 (five‑year groups) | Synthetic cohort, children per woman |
| GRR | TFR × proportion of female births | Daughters per woman, ignoring mortality |
| NRR | Σ(female ASFR × survival to that age) | Daughters per woman surviving; NRR = 1 = replacement |
| Child–woman ratio | Children 0–4/women 15–49 × 1,000 | From census when births are unavailable |
| Pregnancy rate / abortion rate / abortion ratio | Per 1,000 women 15–44 / per 1,000 live births | |
| Completed family size | Total children born to a woman at the end of her reproductive years | Actual cohort, not synthetic |