Hits & Myths: when menstruation doesn't mean ovulation

PUBLISHED : Monday, 05 May, 2014, 9:42am
UPDATED : Monday, 05 May, 2014, 9:42am

Does having regular periods mean that ovulation is regular, too?

The straight answer: No

The facts: Some women take it for granted that just because they menstruate monthly it means that they are ovulatory and, therefore, will not have any problems falling pregnant. But the fact is, just because you have regular periods does not mean that you are ovulatory.

Anovulation - which describes the condition when ovulation does not occur - is not common, but it is a problem for women who want to conceive. According to Professor Ernest Ng Hung-yu, clinical professor of the department of obstetrics and gynaecology at the University of Hong Kong's Li Ka Shing Faculty of Medicine, anovulation generally presents with irregular periods. If you have regular periods, you have a 95 per cent chance of ovulation. Therefore, you can be anovulatory even if your menstrual cycle is seemingly normal.

Ovulation occurs when a mature egg is released from the ovary, a process triggered by the hormone progesterone. The egg then travels down the fallopian tube where it waits to be fertilised. If it is fertilised, conception occurs. Otherwise, the unfertilised egg is shed, along with blood and the lining of the endometrium that has thickened in preparation of pregnancy. This process is called menstruation.

With anovulation, there is no ovulation because progesterone is not produced. However, the oestrogen-induced endometrial accumulation continues, resulting in bleeding, which is mistaken for a period.

Anovulation might be due to a number of factors, among them: stress and anxiety, certain types of medication, excessive exercise, extreme weight loss, obesity and hormonal imbalances (for example, when the pituitary gland or hypothalamus does not produce the hormones needed to trigger ovulation).

Anovulation accounts for about 10 per cent to 20 per cent of infertility cases, Ng says.

If you have regular periods but are anovulatory, you will not experience the mid-cycle abdominal discomfort due to ovulation or the abdominal and breast tenderness due to the increase in progesterone levels after ovulation.

If you are having trouble falling pregnant and suspect you may be anovulatory, it is important to get checked. Your doctor will order a blood test to measure your progesterone level about one week before your next expected period to confirm whether you have ovulated.

A recent survey by the Family Planning Association found that Hong Kong couples have become more positive about childbearing, with the proportion of women wanting children rising significantly, from 12.7 per cent in 2007 to 20.2 per cent in 2012 - the highest since 1992. Correspondingly, the proportion that did not desire any or more children decreased, from 80.8 per cent in 2007, to 63.8 per cent in 2012.

Despite these changing attitudes, birth and fertility rates in Hong Kong are still among the lowest in Asia, mainly because couples are getting married later or putting off having children. Another explanation for this trend is the misconception women have about their fertility, such as having a period means that ovulation has taken place.