Table 2.

Cohort-specific factors estimated from the UPDB used to estimate the size of the nulliparous fraction of females

Age class	Birth years	Census	${\overline{\delta }}_X$	${\overline{L}}_{XY\left(m=0\right)}$	${\overline{L}}_{XY\left(m>0\right)}$	PY(F)
45–49	1891–1895	1940	2.1510E–04	0.5259	0.8954	0.1897
35–39	1871–1875	1910	1.1860E–02	0.4683	0.9326	0.2281
40–44	1866–1870	1910	2.3040E–03	0.4322	0.9054	0.1876
45–49	1861–1865	1910	2.8220E–04	0.3771	0.8679	0.1637

US Census data and UPDB data were binned into 5-year and 1-year windows, respectively. To account for this, single-year values of δ_x, L_xy(m=0) and L_xy(m>0) were averaged over 5 years (and weighted by cohort size) to arrive at the values above.