Ovulation occurs 36-40 hours after a surge of luteinizing hormone (LH). Knowing when you are ovulating allows you to time your sex during your fertile period to maximise your chances of getting pregnant.
How can I check that I am ovulating?
There are a few options:
- Basal body temperature (BBT) chart
Your body temperature increases slightly after you ovulate. To understand your body, you will need to chart your BBT every morning to look for a pattern. You should have sex few days before and after your BBT rises.
- Urine ovulation test kit
These are available over the counter and detects LH in the urine. You should start testing a few days before your expected day of ovulation (e.g. if you have a 28 day cycle, your ovulation date should be around day 14; if you have irregular cycles, take your shortest cycle in the last few months and start testing a few days before the mid-point of your shortest cycle) and continue daily until it turns positive. Once it turns positive, you do not need to test further that cycle. Ovulation usually occurs within 12 to 36 hours – have sex that day and for 2-3 days after to maximise your chance. If you have tried for a few months and not had a positive urine test, you may not be ovulating; see your gynaecologist.
- Blood test for luteinizing hormone
This is to detect the rise in LH in your blood and predict ovulation. Just like the urine test kit, you may need repeat blood tests.
- Ultrasound scans
Transvaginal scans to check follicle growth (follicle is where the egg gets released from) can help time sex as ovulation usually occurs when the follicle reaches about 18mm.
What if I am not ovulating on time?
This could be due to a variety of factors including:
- Polycystic ovary syndrome (PCOS)
- Stress
- Body mass index that is too low or too high
- Intense exercising
- Eating disorders
How can I fall pregnant if I am not ovulating on time?
You still have a chance of falling pregnant even if you do not ovulate on time – so if you are not planning for pregnancy, do use a reliable birth control method.
If you are trying for pregnancy, your gynaecologist will discuss your options for fertility depending on the cause. Lifestyle modifications may be required. Options include ovulation induction and in-vitro fertilisation.
