This past week I have taken two long train journeys. These have allowed me to catch up on some reading. I read “Count Down”. This is a book on fertility by Shanna Swan. She was the scientist who first highlighted the drop in sperm counts around the world in 2017. In previous Newsletters I have highlighted that women are having their first child later and this is why fertility is dropping. The book provides the rationale for why the delay matters. I have also highlighted the drop in male sperm count and she explains why this is happening and its impact. She points out that female fertility is also falling for the same reasons.
Best Before 35
The data is unambiguous. Bewtween the ages of 25 and 35 unprotected sex at the correct time of the month will result in pregnancy between 25% and 35% of the time. There is a 90% chance that the child will be carried full term and a 1 in 900 chance that it will have Down Syndrome. As time goes by the numbers deteriorate at first slowly and then very quickly. At 35 the chances of conception drop to 20%. At 37 it drops to 15% and at 40 it is down to 10%. By 45 it is 5%. Miscarriages increase to 25% at 35 and rise to 40% at 40. Down Syndrome incidence increases from 1 in 300 at 35 to 1 in 50 at 45.
It is clear that delaying becoming a parent reduces the chances of success. It becomes increasingly difficult to carry a healthy child to full term. Why does this happen? It turns out that men and women are equally responsible for the reduced chances. Data from the clinics treating fertility problems show that 25% to 33% of the problems are due to the woman. Exactly the same proportion come because of male issues. The balance are due to the combination. Each individual could probably have a child but not with this partner. Exactly the same story is true of miscarriages. Men and women share the responsibility. With age a man’s sperm will have an increased proportion of “scrambled” DNA. As the impact on the foetus emerges the body rejects it.
Why do couples delay starting a family if the data is very clear. Surveys show that women over estimate the chances of getting pregnant at all ages. Surveys of new mothers show that 83% had under estimated how long it would take to have a child. They were also much too optimistic about the chances of a mis-carriage. The situation gets worse as women age. At 35 they over estimate the chance of a woman getting pregnant at 40 by 50%.
Will couples respond to the data? They adapted during the early stages of the demographic transition. The number of children per female aligned with the falling child mortality. Will reality dawn and couples start to have children earlier? Will children per female therefore improve? Instead will the economic arguments or the lure of a far from perfect IVF system win? The UK data shows the current success of IVF to be 32% at 35 or under. This drops to 25% between 35 and 37, 19% between 38 and 39 and 11% for women aged 40 to 42.
It's all in the Environment
These numbers are all taken at a single point in time. Unfortunately they are changing. In each successive decade the chances are reducing. Something else is going on. The sperm bank industry was worth over four billion dollars in 2018. That is forecast to grow to five and a half billion by 2025. It is a source of a lot of the information on the global health of sperm. For example, in 2003 69% of applicant donors at one major US sperm bank were accepted. By 2013 that number had dropped to only 44% despite a massive recruitment campaign. Sperm counts are dropping and the health of the sperm declining. Mobility especially has been falling all over the world. Quality donors are more and more difficult to find.
Behaviours are having an effect on both male and female fertility. Body weight, smoking, alcohol and stress reduce reproductive health in both sexes. Over and under exercising is causing problems as well. The good news for men is that these effects are reversible. Diet and correct exercise can reverse many of the causes and restore fertility.
For women the problem is more complex. Eggs cannot be replaced. A woman is born with all the eggs she will ever have. That may be 1 or 2 million when she is born but they die and by puberty she will be down to 300,000. At 37 she is down to 37,000. As women age, egg quality as well as numbers declines. Inappropriate behaviours reduce the egg reserve further. At the same time the incidence of endometriosis and other fertility threatening diseases increases.
Shanna Swan highlights the impact of chemicals in the environment on both humans and animals. Lake Apopka in Florida is often used as an example. The lake is polluted with the run off of sewage and pesticides. In 1980 it also suffered a major pesticide spill from a nearby factory. Studies of the alligators in the lake, show high abnormalities in the reproductive organs. The result is that successful hatching of eggs is down to only 5% compared to benchmarks of 85% from unpolluted lakes.
There are classes of chemicals that can influence the production of hormones in humans and animals. They are in everything from plastics to pesticides. Phthalates are for example used to make plastics more pliable. They appear in food storage containers, flooring and even wallcovering. They can influence the production of testosterone. In men this reduces the sperm count and induces more misshapen sperm.
Bisphenol A is used in epoxy resins, the lining of food cans and even thermal receipt paper. It mimics oestrogen. Men with detectable levels in their urine were four times more likely to have poor sperm. The effects on women are greater. Those with high concentration in their blood have increased difficulty becoming pregnant and have an 83% chance of miscarriage in the first trimester.
The impact is not only on this generation but future generations as well. Unborn babies are susceptible to exposure at certain points in pregnancy. These same chemicals can impact their fertility, sexuality and sex drive. All this happens before they are even born. Unfortunately regulation is very poor in many parts of the world. Food and drugs are tested rigorously for negative effects before being allowed to be used. Chemicals are not.
Cumulative exposure to these chemicals comes with age. Given the underlying time limited nature of fertility there is even more logic in having children earlier. Thirty five must become a “Best Before” date.
Migration and the Ukraine Conflict Update
An article in the Financial Times this week provides an alternative perspective on my Newsletter on Migration (#050). In the years before declaring war on Ukraine, Putin was campaigning to increase the birthrate in Russia. It had fallen below replacement level in 1989. It fell as low as 1.2 children per female at the start of this century but had risen to 1.8 five years ago. As the article points out the war is having a triple negative impact. Sanctions will reverse economic growth and put pressure on families. Young men will die in the war. Migration is increasing. This is all storing up problems for the future.
The article estimates that some 70,000 young men from the tech sector have left Russia in the four weeks since the start of the war. It is thought that 100,000 more will follow this month. They are talented and this has given them mobility. Russia has offered exemption from military service for the higher educated. It has even subsidized their mortgages. All to try to keep them.
Israel in particular has seen the opportunity this presents. They have offered fast track “green visas” for Russians and Ukrainians with key skills. They estimate that as many Russians as Ukrainians have emigrated to Israel. The fight for migrants appears to be heating up!