Q: I am 48 this year and I really want to start a family. I have never been pregnant before. Tests done 15 years ago showed that my reproductive system was fine.

I have spoken to my obstetrician and gynaecologist and he has advised me against conceiving because I am currently on tamoxifen. I am taking this hormonal medication as I had breast cancer.

My friend carried her baby to full term when she was undergoing hormonal treatment for cancer.

Her child is now five years old and healthy.

Is there no way that I can have a child of my own?

A: It is not easy to make a comparison between you and your friend without knowing more details, such as her age at the time of the pregnancy, the type of cancer she had and the type of treatment she received.

I understand that you are taking tamoxifen to reduce the risk of a recurrence of breast cancer.

There are two issues here: conceiving at the age of 48 and conceiving while on tamoxifen.

CONCEIVING AT THE AGE OF 48

While tests of your reproductive system were normal 15 years ago, a significant length of time has passed and your body will have changed.

The most important of these changes is a decrease in the number of oocytes or eggs.

In addition, with increasing age, there is a greater chance of you developing conditions that can also affect your fertility.

These include endometriosis (a condition in which cells that usually line the uterus grow abnormally outside of it), endometrial polyps (growths in the inner lining of the womb which can turn cancerous) and fibroids (non-cancerous growths in the womb).

Unlike men, who continue to produce sperm well into advanced age (the oldest man to father a baby is a 96-year-old man in India), women are born with all the eggs that they will ever have.

It is estimated that a baby girl is born with about 1 to 2 million oocytes.

By the time she reaches puberty (when female sexual hormones are produced to cause bodily changes), which usually starts in girls between the ages of 10 and 14, this number will have been reduced to about 300,000.

Over the course of the next 30 to 40 years, approximately 400 oocytes, after maturing, will be released from the ovaries during the process of ovulation.

However, by the age of 40, perhaps only 25,000 oocytes remain.

The other oocytes degenerate, having never reached full maturity and ovulation.

By the time menopause happens (when menstruation stops), which usually occurs between the ages of 50 and 55, fewer than 1,000 oocytes are left.

Therefore, the likelihood of pregnancy is extremely low at the age of 48.

It is estimated that the chances of becoming pregnant spontaneously above the age of 45 are 1 to 3 per cent at best.

Furthermore, there is an increased risk of miscarriage, which is above 50 per cent in those over the age of 45, compared with below 6 per cent for women aged under 35.

Egg quality decreases with age and the risk of chromosomal abnormalities increases. For example, the risk of a woman having a baby with Down syndrome is 1 in 16 at the age of 48 compared with 1 in 400 at the age of 35.

Even with assisted reproductive techniques such as in-vitro fertilisation, the live birth rate is no more than 1 to 2 per cent when women aged 45 or over use their own eggs.

In Singapore, the law states that licensed assisted reproduction centres may treat women aged 45 and above only after a successful appeal to the Director of Medical Services of the Ministry of Health, on a case-by-case basis.

CONCEIVING WHILE ON TAMOXIFEN

Most doctors would recommend that tamoxifen is avoided during pregnancy, and that effective contraception is used until at least two months after you have stopped taking tamoxifen.

Problems that have been reported with tamoxifen use during pregnancy include vaginal bleeding, miscarriage, congenital malformations and foetal death.

Furthermore, the long-term effects of tamoxifen and whether it may increase gynaecological cancer in daughters are unknown.

In animal studies, the use of tamoxifen in pregnant rats has been associated with breast cancer in female offspring.

I am sorry that I do not have any good news for you.

If you have any further questions, I would suggest that you make an appointment with a gynaecologist.

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