Why Can’t I Conceive Again?

Planning for a second child in your late thirties? Here are 5 things you need to know, says fertility specialist, Dr Ann Tan.

It is natural to assume that if you have successfully conceived once, you have little to worry about when planning for your next child. However, as a fertility expert, I have observed that the number of couples seeking medical assistance with conceiving their second child is on the rise.

Couples tend to be in their thirties when they are trying to conceive their second child

This is to be expected as the average age of first-time mothers in Singapore has gone up. This can be attributed to a range of socio-economic factors including couples opting to get married a little later in life. It follows that many parents are well into their thirties by the time they try to conceive again.

Many of my clients share experiences similar to C’s who is in her late thirties:

“My husband and I planned to try for our second baby once our eldest turned 3 or 4. While we were committed to our timeline and did our homework, setting it into action wasn’t as simple as we thought it would be.

“We know of many couples my age who have the same issues. No matter how conscientious we were with our attempts to get pregnant, we were met with a heart-breaking negative on our pregnancy test month after month.

“Our challenges are usually stress- or age-related. Most of the people we know have to rely on IVF [in vitro fertilisation].”

Why it is not as easy to conceive the second time around

Most couples who are planning to conceive again do not realise that the gap of just a few years between their first attempt and they're second affects fertility in both the husband and the wife. The following are key factors to bear in mind:

1) A woman is born with all the eggs she will ever have

She does not replenish her reserve of eggs in her lifetime. By the time a woman turns 32, her fertility begins to decline. At birth, a woman has 1,000,000 eggs. By puberty, her egg reserve will have halved, and by her twenties, she has about 200,000 eggs.

The decline starts slowly in her twenties, more rapidly in her thirties, and steeply in her forties. Unfortunately, the rate of decline and the number of eggs that remain in her reserve at each decade of a woman’s life is variable. The only way for her to know how fertile she is at any given time is to get tested and reviewed. Ignorance is not bliss.

Tip: ​Get your Anti-Mullerian hormone (AMH) tested to understand your personal ovarian reserve. The AMH is a hormone secreted by cells in developing egg sacs (also known as follicles). The test provides an indication of your egg count. AMH does not change during your menstrual cycle, so the blood sample for the test can be taken at any time.

2) Older eggs are more likely to contain abnormal chromosomes

When a woman is 35 years-old, 50 percent of her eggs are normal. When she is 40 and above, only 5 to 10 percent of her eggs are normal. It follows that the corresponding chances of normal conception and babies become more difficult.

3) Gynaecological complications tend to increase with age
Over time, a woman may develop ​fibroids​ or ​polyps​ within her uterus.​ Endometriotic cysts​ may also form within her ovaries. All these can diminish her ability to conceive by damaging either the uterus or her already fragile egg reserve.

Medical jargon explained:
Fibroids​ are growths that develop in and around the womb. They can obstruct implantation and reduce the chances of pregnancy by being in the wrong place (for example, they might protrude into the inside of the uterus — these are called submucosal fibroids). The presence of many large fibroids may also increase the risk of preterm (also known as premature) labour.

Polyps​ are little growths the size of a raisin or grape. These tend to prevent sperm from swimming up to the fallopian tubes or obstruct the implantation of the embryo.

Endometriotic cysts​ are commonly associated with infertility. They are fluid-filled growths that develop when the lining of the uterus grows deep within a woman’s ovaries. Also known as chocolate cysts, they impact the quality of the eggs and diminish the egg reserve over time.

4) A couple is usually at a different stage in life by the time they try for their second child

In their mid-to late-thirties, both husband and wife are likely to have advanced in their careers and maybe juggling more stress than they were when they were younger. They may also have less time to commit to regular exercise and good nutrition.

These factors have a knock-on effect and at this point in life, medical disorders tend to develop. Diabetes, hypertension and thyroid disorders may affect the chance of fertility. They can also make the pregnancy more complicated and difficult to carry.

5) Caring for a young child is exhausting. Parents juggling a toddler often have less energy to try to conceive another baby

This may sound trite, but it is true. It is a factor that is often overlooked. Unfortunately, a baby or toddler co-sleeping in his or her parents’ bed is a very effective contraceptive method!

It is important to speak to your doctor early to understand how fertility can change over time. This can affect your plans and help you better understand your options.

This article is written by Dr Ann Tan, Medical Director, Virtus Fertility Centre Singapore