This week, we’re examining sexuality data from the 1960s, in celebration of the upcoming final half-season of “Mad Men” beginning Apr. 5th.

On “Mad Men,” two significant female characters, Don’s wife Betty Draper (January Jones) and his subordinate Peggy Olson (Elisabeth Moss), gave birth to sons. (Oops, spoiler alert?) While each character made different decisions regarding their progeny, it became a pivotal moment for both of them.

Tracking the number of live births within a population is an essential checkpoint to determine how healthily a population is growing. We’ve already looked at population and marriage stats from the 1960s; now let’s look at birth stats from the decade.

I found a table put together by the Centers for Disease Prevention and Control (CDC) cataloging registered live births from 1933 to 1998, breaking down the data by the age and race of the mother. For our purposes, we’ll look at age only and narrow it down to mothers ages 15-49.

Here’s the data table:

But the patterns are a little hard to see. So I made a line graph:

Now we can begin to see some patterns.

It appears that 1964 was a tipping-point year, as some of the age-ranges pivoted from their determined patterns at that year. The number of mothers ages 20-24, the largest group in the series, dropped below 1.4M+ that year, and settled around 1.3M+-1.5M+ for the remainder of the decade. Likewise, the number of live registered births for the 25-29 cohort hit 1M+ that year for the last time that decade. For the rest of the 1960s, births for women ages 25-29 stayed within the six-figure range.

Previous to 1964, women ages 30-34 numbered around 600K+ live births. But 1964 began a drop into the 500K+ range for a couple of years, before ending the decade within the 400K+ range.

Women ages 15-19 (well, teens) stayed within the same range of births throughout the decade (585K+ to 605K+, with an outlier of 621K+ in 1966). But the line graph above makes it appear as if the cohort had a more dramatic rise, but that’s because it’s set off by the 30-34 range’s changes.

In terms of the “Mad Men” characters, Peggy Olson would’ve been 21 years old, and would’ve given birth around 1960. That places her in the largest age cohort of that year. (Ages 20-24 outstripped the next-highest range, ages 25-29, by 334K+ births.) Betty Draper was around 31 years old in 1963 when she gave birth. So she was within the largest of the age ranges that year which didn’t hit 1M+ live births, but still on the downswing of common pregnancies. (Women ages 30-34 registered 610K+ live births).

It seems that showrunner Matthew Weiner’s obsessiveness towards period accuracy extended even to birth ages of his female characters.