By Dr Geeth Monnappa
The timing of egg release (ovulation) and its knowledge is vital to a couple planning a pregnancy.
This allows a couple to be sexually active at the right time, thus increasing their chances of a successful pregnancy .
Most women are unaware of the fertile period,which is the period around ovulation, when the chances of pregnancy are maximum. A sperm has a life span of 3-5 days,while an egg has a much shorter life span, lasting 1-2 days.Hence the fertile window begins about 5 days prior to ovulation and lasts for 2 days post ovulation.
In a woman with a regular 28 day menstrual cycle, ovulation occurs on the 14th day of the cycle.Hence, the fertile window lasts from the 10th to the 16th day of the cycle. However, in most women, menstrual cycles vary from 21-35 days , thus causing a variation in the timing of egg release. In women with irregular cycles like those with PCOS, timing ovulation can be particularly difficult as their periods don’t normally adhere to a pattern.
Tests to determine ovulation:
- Basal body temperature(BBT):
As early as 1906, it was noticed that the body temperature increased marginally after ovulation due to the hormone progesterone.
Measuring the oral/ rectal/ vaginal temperature each morning will clearly denote a fall in the basal body temperature just before ovulation followed by a rise of temperature by 0.5-1 degree F above the baseline after egg release suggesting ovulation.
- Ultrasonography:
Ultrasonography is the gold standard for detecting ovulation. However, as it’s inconvenient, expensive and requires trained personnel; it’s often not the first method used to detect ovulation. In an infertile couple undergoing treatment, no other method is as reliable as an ultrasound .
On ultrasonography, we monitor the growth of the follicle until it reaches 18-20mm.
This is a mature follicle that is likely to rupture.
A reduction in the size of a mature follicle along with an increased echogenicity within the follicle, free fluid in the pelvis and changes in the appearance of the endometrium ( inner lining of the uterus) confirm ovulation.
- LH kit:
Luteinizing hormone , a hormone secreted by the brain, starts to rise 35-44 hours prior to ovulation and peaks about 10-12 hours prior to egg release.
This rise is detected in over the counter LH kits which denote 2 lines similar to a positive pregnancy test if the LH surge has occurred.
As it’s a simple, inexpensive, non-invasive test as compared to an ultrasonography, it’s often employed by women to detect their fertile window.
Women are instructed to check their urinary LH with the kit at least once a day from day 10 of the cycle( day 1 being the first day of period) until a positive test is obtained. Ovulation occurs within 48 hours of a positive test.
In a few conditions like endometriosis and in 10% of normal fertile women, LH surge maynot be followed by ovulation and the follicle maynot rupture despite the hormonal changes that indicate imminent ovulation.This condition is called luteinized unruptured follicle and could lead to a false positive urinary LH test.
- Serum progesterone:
Serum progesterone levels above 3ng/ml in the second half of the cycle indicates ovulation.This blood test denotes the hormonal changes that occur post egg release when the corpus luteum formed by the follicle that has ruptured,produces the hormone progesterone to help sustain a pregnancy.
- Cervical mucus:
Observing changes in the vaginal discharge during the menstrual cycle is probably one of the easiest and simplest methods to detect ovulation. The cervical mucus around ovulation becomes thin, watery, egg-white in color, excessive and stretchable between two fingers. During the rest of the month, the mucus tends to be thick, scant and viscous. This method however, is unreliable in women having a vaginal infection due to a change in the consistency of the vaginal discharge.
Simple methods like BBT and changes in the cervical mucus can be employed by women to detect their fertile window when they begin to try for a pregnancy.
If the above methods fail, home LH kits may be used and the gynecologist can be notified if the test is not positive throughout the month. Ultrasonography is the most reliable indicator of ovulation and is often employed when the above methods fail or if a couple needs treatment to get pregnant.
(The author is a Senior consultant, obstetrics and gynecology, Fortis hospital, Richmond road, Bengaluru. The article is for informational purposes only. Please consult medical experts and health professionals before starting any therapy, medication and/or remedy. Views expressed are personal and do not reflect the official position or policy of the FinancialExpress.com.)
