New article says old science was wrong, female fertility does NOT fall off a cliff in mid-late 30's

[astro]

Is what we assumed to be scientific fact now shown to be wrong? Interesting article

How Long Can You Wait to Have a Baby?

The best way to assess fertility might be to measure “cycle viability,” or the chance of getting pregnant if a couple has sex on the most fertile day of the woman’s cycle. Studies based on cycle viability use a prospective rather than retrospective design—monitoring couples as they attempt to get pregnant instead of asking couples to recall how long it took them to get pregnant or how long they tried. Cycle-viability studies also eliminate the need to account for older couples’ less active sex lives. David Dunson’s analysis revealed that intercourse two days before ovulation resulted in pregnancy 29 percent of the time for 35-to-39-year-old women, compared with about 42 percent for 27-to-29-year-olds. So, by this measure, fertility falls by about a third from a woman’s late 20s to her late 30s. However, a 35-to-39-year-old’s fertility two days before ovulation was the same as a 19-to-26-year-old’s fertility three days before ovulation: according to Dunson’s data, older couples who time sex just one day better than younger ones will effectively eliminate the age difference.

[Smeghead]

The numbers they give in this article for the risks of chromosomal abnormalities a quite a bit lower than the ones I’ve seen in the literature, but I’d have to poke around to find a citation.

[rhubarbarin]

For me this is a big duh. I’ve met such a large amount of women who had healthy babies they got pregnant with naturally within a few months of trying, between the ages of 35-45.

[Tom_Tildrum]

according to Dunson’s data, older couples who time sex just one day better than younger ones will effectively eliminate the age difference.

This is such a freakishly inaccurate reading of Dunson that it’s hard to know how to respond. The chart that the Atlantic author is reading is here (pdf) at p.3. For each age group, fertility climbs each day until it peaks at 2 days before ovulation, then it decreases each day. On any given day, the fertility rate of the younger couples (the height of the line) is much higher than that of the older couples. The overall likelihood of pregnancy in a cycle (the area under the line) is much greater for younger couples.

Yes, it’s trivially true that the fertility rate for 35-39 couples at Day Ovulation-2 is the same as for 19-26 couples on Day Ov-3. But that doesn’t erase the age difference; it highlights it. It’s saying that at the very best, the older couple can only achieve a level of fertility that younger couples achieve and surpass earlier in the cycle. Look at Day Ov-2 for both cohorts: The younger couples are almost twice as likely to conceive. That same disparity is present to some extent every day.

[even_sven]

But how are we going to shame women by offering the impossible options (don’t have kids before you can afford them, but for gods sake don’t be selfish waiting for the corner office, do you want to be a cat lady)?

[Malacandra]

That’s right, because biological facts exist only to shame women.