Time waits for no ovary

Study, travel, career, babies — do women actually have time to fit it all in? Dr Andrew Murray looks at the increase in couples needing help with fertility.

If you speak to anyone in their thirties, they are pretty likely to know someone who is struggling to start a family. We are conditioned to fear getting pregnant throughout our teenage years and early twenties, yet when the time comes to actually want to get pregnant, for many, it starts to become a struggle. It raises the questions: are fertility problems becoming more common? And are fertility rates on the decline?

Leaving it until later
Back in the early 1960s, when the 'baby boom' was in full flight, women were having, on average, three or four children each. The quarter-acre section, with mum at home, dad at work and the kids running around, now seems like some utopian fantasy. Back then the most common age-group having children was women aged 20-24. Fast-forward to the most recent census data and now the most common age group having kids are women aged 30-34. The average age of women having babies is 31.

There are a number of reasons why this has happened. Firstly, the tremendous contribution safe and effective contraception has made in allowing women to plan their fertility has meant women are now able to take better control as to when they choose to have children.

Women have also made significant progress in achieving equality in the workplace and are now encouraged to seek careers in areas that were traditionally male-dominated. “Girls can do anything” was the catch-cry of the late seventies and early eighties. Years are set aside for study as tertiary training has become almost essential in order to improve one’s employment prospects.

Being an island nation, Kiwis have had a long-held tradition of the ‘great OE’ and, consequently, many women are choosing to travel and see the world before they are ‘tied down’ in a long-term relationship with kids.

For a long time we have also been hearing that women are waiting for Mr Right – someone who ticks all the boxes: good-looking, wealthy, practical, sensitive, gets on well with your mother… Basically women are urged to not settle for second-best.

Indeed, girls can do anything, but perhaps we need to stop using this expression so flippantly and ponder, can girls do everything? 

Man drought
Although some women may be getting caught up in trying to find this 'perfect' guy, I very much doubt it is the majority. And even so, this is not just women being fussy – the ‘man drought’ is real. In the 30 to 40 age bracket, there are significantly more single women than there are men.

Census 2013 figures show the number of men to go around is at an all-time low. For every 100 women looking to snag a Kiwi chap aged between 25 and 49, on average about nine will miss out.

On a weekly basis (in my practice) I meet successful, attractive women who would love to start a family with someone, but they simply can’t find a guy who is willing to take the plunge into parenthood. It is often the blokes who are refusing to commit to starting a family. Life is good with their gadgets, sports and mates and they think, “Why settle down? There’s plenty of time for that later. Right?”

Time waits for no ovary
You need three basic ingredients to make a baby: eggs, sperm and somewhere to grow the baby (uterus or womb). The phrase ‘biological clock’ deserves our attention. Women are born with all of their eggs (about 1-2 million), and they never make any new ones. In fact, before a baby girl is born she has already lost over 70% of her peak number of eggs. In the ovaries there is a constant attrition of eggs due to a normal process called apoptosis. Apoptosis (programmed cell death) is a normal and necessary process that gives all of the cells in our bodies a limited lifespan. Without it, cells continuously divide and become immortal, which is what happens in cancers. Eggs just happen to be very good at apoptosis. By the time a girl reaches puberty she will have around 400,000 eggs left, by age 35 there will be 25,000, until she reaches menopause and runs out altogether. This rate of egg-loss is genetically determined by genes on the X-chromosome, so if your mother went through menopause early there is a risk you could have a faster rate of egg-loss as well. Other environmental factors accelerate egg-loss too, for example, smoking, cancer treatment, or previous ovarian surgery.

So quantity decreases with age, but what about quality? As women get older, many of their remaining eggs have genetic abnormalities. Imagine a jar of jellybeans on the day you are born – this represents the total number of eggs you will ever have. The ‘good eggs’ are the coloured jellybeans and the ‘bad eggs’ are the black jellybeans. Most people don’t like black jellybeans, so if you were to pass the jar around sharing them out over time, eventually the majority of the jellybeans left in the jar would be black ones.

In other words, the older a woman is, the higher percentage of ‘bad eggs’ she has resulting in a lower chance of conceiving naturally. At age 30, the chance of conceiving naturally and having a baby is around 20% per month, at 35 it is 15%, by age 40 it is 5%, and by 45 it drops to about 1%. This also explains why miscarriages and abnormalities like Down Syndrome increase in likelihood as women get older.

Men have a biological clock too, it just ticks in a different way. Men aren't born with any sperm, just the precursor cells to make them. Sperm production begins at puberty and men continue to make new sperm their entire lives. Sperm are like DNA delivery vans – basically vehicles to get the man’s DNA to the woman’s egg. The average time span to make a new batch of sperm is 72 days. Environmental factors such as smoking, alcohol or being overweight can affect sperm quality. As men age, the DNA in the sperm is more susceptible to damage which may increase the risk of miscarriage, and also might contribute to the higher incidence of autism or schizophrenia in the children born to older fathers.

The eggs of younger women can repair some of sperm's DNA damage at fertilisation, but they lose that ability as they get older.

The uterus can carry a pregnancy well beyond when the eggs run out. The stories of women carrying babies into their sixties have happened through the use of donor eggs. What has to be remembered here is that although a women can still successfully carry a pregnancy many years after her own eggs have run out, the likelihood of pregnancy complications from being older increase markedly with age, including high blood pressure, diabetes, postpartum haemorrhage and deep vein thrombosis.

Basically, fertility problems are becoming more common because we are choosing to have children later. We are as fertile as we ever have been – we are just leaving it until a time that the background chances to conceive have naturally reduced.

Best before date
Studies have shown that both men and women overestimate their fertility potential. A 2012 study of American College students found that 67% of women and 81% of men overestimated the age which fertility potential declines, with men estimating the age significantly higher than women.

Why do we overestimate our fertility? Phrases like “Forty is the new thirty” obviously don't help, and popular media has a role here. If you look at any news-stand there are stacks of magazines filled with celebrity older mums and dads, smiling back at the paparazzi while juggling their Starbucks coffee and the newborns they have had in their late thirties and forties. What is often not told in such stories is that many of the celebrity older mothers have needed to use donor eggs from younger women to create their families.

Today there are many reasons both men and women are choosing to delay starting a family, and this is the single biggest driver of the increase in couples needing to seek fertility help. Now, one in five couples wanting to start a family will still not be pregnant after a year of trying.

What should we do?
We need to encourage men and women to consider family planning as part of their career planning. Increasing opportunities for women to interrupt training to have children and designing roles that allow for part-time contributions for a short time while women can have their kids need to be considered. And, in my opinion, men need to step up, grow up and commit, and stop being so fickle.

Technology has changed our lives in many ways, but reproduction is one area where Mother Nature still holds a strong influence. Even with IVF you see a decrease in conception rates. A woman at the age of 35 will have about a 42% chance of having a baby per attempt, while a woman aged 42 will have a 15% chance.

Egg-freezing is another new technique which allows women to freeze their eggs and preserve them for use at a later stage. The younger the woman is at the time of freezing her eggs, the more likely she is to produce viable embryos. We are pleased that we can now offer this option at Fertility Associates. This has also been very useful for people going through cancer treatment who want to protect their future fertility.

The Anti-Müllerian Hormone (AMH) test is a simple blood test that highlights hormone levels and can suggest when a woman might have lower fertility than expected for her age. So, if a woman has the AMH test in her early thirties and finds out that she will have a lower-than-average egg reserve, she can make some decisions around timing and the option of preserving eggs for future use. An AMH test does not exclude other possible causes of reduced fertility, but it is a step towards being informed earlier.

The best advice I can give to women in their thirties is to talk to your GP, and work through all of the options. Even if it still feels light years away, understanding your own unique fertility situation and the options you have available today, is a much better solution than waiting until life falls into place.

Dr Andrew Murray is Medical Director of Fertility Associates Wellington. He is also a senior lecturer at Wellington School of Medicine and a consultant obstetrician and gynaecologist at Wellington Hospital.