How baby-making late in life evolved into subfertility and infertility, difficult conception, too long TTC

Way back, in the pre-contraceptive Pill days, the difficulty to become pregnant was not a widespread phenomenon, and mums were  younger than many are nowadays. If you want to see graphical proof of how the phenomenon came about in the previous century, review the attached paper Google evidence of increasing prevalence of subfertility. Should you not be a subfertility or infertility sufferer, and therefore not familiar with the acronym, TTC stands for Trying To Conceive.

The evolution of subfertility and infertility (as a big-time societal phenomenon) in the U.S. can be summarized based on data from http://www.infoplease.com/ipa/A0005074.html#ixzz2GBMSkUKy  [Information Please® Database, © 2007 Pearson Education, Inc.] as follows.

In 1940, births to mothers over 29 years old (30 to 49) were apparently almost as numerous as births to mums of the optimal fertility age 20-24: The ratio of 30-49 years old to the optimal-age group was 0.91 [here referred to as ratio a) =  data for 30–34 plus 35–39 plus 40–44 plus 45–49, this sum divided by data for 20–24], and the number of births in the most fertile age group of mums represented 31% of all births in the U.S.

In case you did not check out the above-linked attachment https://biozhena.files.wordpress.com/2012/12/google-evidence-of-increasing-prevalence-of-subfertility.pdf : The high number of 1940 births to older mothers [high ratio a)] is not so surprising in view of the growing number of books on subfertility and infertility in the 1940s, as seen in the respective Google Ngrams shown here and discussed in the attached PDF paper.

Ngram 3: infertility and contraception

In the present analysis of the historical birth rates, the age group of 25-29 is considered kind of neutral (neither optimal nor too old) whereas the 30-34 years old group is included among the too old ages for optimal fertility. This inclusion could be disputed – if we did not face the subfertility/infertility phenomenon, in which age is a significant factor. In any case, excluding the 30-34 age group from the aged-motherhood definition only delays the trend reversal – observed below in 1980 – by a decade.

I interject here a citation from the post referenced and linked at the end of this post, so that you’ll be well aware of the link between conception difficulties and advancing age, and of the adverse effect of the use of the Pill.

QUOTE: People have a hard time accepting that getting pregnant is not as easy as expected, when they finally decide to want a baby – usually way too late, and after her use of the Pill. The drug makes healthy young women in their best years to postpone family- and baby-making, it damages their cervical S-crypts thus causing difficulty to conceive and, by encouraging promiscuous sex life, it has caused an enormous increase in the prevalence of sexually transmitted diseases that also lead to infertility. Not just a double whammy, a triple whammy on womankind.  Sad, sad, sad. … Advanced age of the would-be Mum works against her on account of the Mother Nature’s Probabilistic Rules and Regulations of Baby-Making… END QUOTE.

An obgyn’s article on female subfertility in the Lancet invokes “two main factors that determine subfertility: duration of childlessness and age of the woman”. It is not likely that an obgyn would be as critical of the Pill as yours truly, although there have been exceptions. No further comment on this is needed or offered in this blog post. Instead, I share that another medical article from Britain reported that “the incidence of infertility was 0.9 couples per 1000 general population. The average age of women was 31 years, and the average time attempting conception was 18 months… At 12 months, 27% of all couples in the study achieved a pregnancy spontaneously and a further 9% with treatment.”

Here are the 1940 US birth statistics data from the referenced infoplease.com source:

Year	Total	Under 15	15–19	20–24	25–29	30–34	35–39	40–44	45–49
1940	2,558,647	3,865	332,667	799,537	693,268	431,468	222,015	68,269	7,558

And this is the calculation for the present analysis of the data:

a) 729,310/799,537 = 0.912

(ratio a is the sum of births to age groups from age 30 to age 49 divided by births to age group 20 – 24)

b) 799,537/2,558,647 =  0.312

(ratio b is births to age group 20 – 24 divided by total births in 1940)

By 1950 and 1960, the trend was good because ratio a) declined from 0.91 to 0.86 and then to 0.80 while the number of optimally aged young mothers rose slightly to 32% and then to 33.5%. These pre-Pill years were good years from this perspective, and the trend continued – even after the contraceptive Pill was introduced (in the 1960s), at least initially.

In 1970, there was a drop in the total number of births from the total of 1960 (4,257,850 births) and a dramatic drop in the number of births by aged mothers [ratio a) was 0.47] – and the births by the most fertile age group were up to 38% of all births. As though the contraceptive Pill worked in this sense (but only if we do not look at the significantly increased births by underage girls, especially the under 15)… Here is the 1970 data from the above source:

Year	Total	Under 15	15–19	20–24	25–29	30–34	35–39	40–44	45–49
1970	3,731,386	11,752	644,708	1,418,874	994,904	427,806	180,244	49,952	3,146

Unfortunately, in 1980 – that’s some 20 years after the Pill was introduced – the trend started to reverse while the total births continued to drop (and underage births dropped, too): Ratio a) of the number of aged mothers’ births to the most fertile age group’s births rose to 0.58 and births by the most fertile 20-24 year old mums represented now only 34% of total US births. The bad trend toward older-age motherhood continued.

By 1990, there were even more births to aging mothers than births to the most fertile age group, with ratio a) standing at 1.15 and the number of births to mothers of the optimal age group having dropped to a mere 26%.

The bad trend continued so that in 2000 advanced-age mothers exceeded the optimal-age group with ratio a) at 1.45, and with the optimally aged mums at 25% of total births. The trend continued further so that in 2009 advanced-age mothers exceeded the optimally aged mums by a factor of 1.53 [= ratio a)] and the optimal age group’s births dropped to 24% of total births. Data for 2009 are the most recent available data.

Tamara de Lempicka Quattrocento, 1937

Is the difference between way back and now the reason for one other elevated readership statistic here on bioZhena’s Weblog? It is intriguing to see that during the months of the highest numbers of US births/deliveries (late summer and autumn, well before the year-end Holiday Season), a highly viewed post this year was the one published around the time of Mother’s Day: Why too many young and not so young ladies could NOT receive flowers on Mothers’ Day. Why so many trying-to-conceive, why so much infertility = https://biozhena.wordpress.com/2012/05/14/why-too-many-young-and-not-so-young-ladies-could-not-receive-flowers-on-mothers-day-why-so-many-trying-to-conceive-why-so-much-infertility/ Say thank you to the social and medical advances of the twentieth century – primarily those of chemical birth control, the Pill.

What do you think of all this?

P. S. The Alphabet of bioZhena (glossary/primer) is at https://biozhena.files.wordpress.com/2020/01/aaee-the-alphabet-of-biozhena-011207-with-tracking.pdf

Tags: bioZhena, conception, fertility, folliculogenesis, NFP, pregnancy, sub-fertility, trying-to-conceive