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Calculating Ovulation

When you’re trying to get pregnant, it’s useful to learn how to calculate ovulation. You can do this by measuring your basal body temperature (BBT) – your body temperature when you wake after a normal night’s sleep.

It’s easy to do. Just take your oral temperature, using a thermometer that measures in tenths of degrees, first thing in the morning before you eat or begin to move about.

Record your temperature every day, beginning with the first day of the menstrual cycle. Also log any events that may affect your temperature or fertility, such as bleeding, sleeplessness or illness, and when intercourse takes place.

Some women ovulating normally may not have a rise in temperature. Also, many other factors can affect your BTT, such as a fatigue or cold.¹

A rise in body temperature of about half a degree around day 14 of an average 28-day cycle suggests this is your ovulation date – although it isn’t proof that you are ovulating.

Download basal body temperature charts to keep track of your ovulation.

The key practical limitation of this method is that the BBT chart may help you determine when the ovulation is taking place, but only after it has happened. At this time your “fertile window” is over until the next cycle.

If your cycle is regular,you can use this simple ovulation calculator to help determine days when you have the highest chances of getting pregnant.

Ovulation prediction kits

These are simple, inexpensive kits bought from a pharmacy that detect the surge of luteinizing hormone (LH) found in urine shortly before ovulation. The key advantage of the ovulation prediction kits is their ability to predict ovulation before it takes place still within your fertile window. However, not all women who ovulate will have an LH surge that will be detected using these kits.¹

The chances of conception are greatest within the 6-day period ending on the day of ovulation.² If your cycle is irregular, shorter than 21 days or longer than 35 days, ask your doctor for help with determining your fertile phase.

Sexual positions and conception success

There is no scientific evidence that particular sexual positions or preventing sperm leakage from the vagina affects chances of getting pregnant in any way.²

Still, many couples do favour certain positions hoping that they make a difference. This is perfectly fine, as long as they make your sex life more fun and do not introduce unnecessary stress! The most important thing is that you and your partner feel comfortable and sex does not become a chore.

Some commercially available water-based lubricants and petroleum jelly have been found to affect sperm motility². Ask your doctor about lubricants that can be used safely while trying to conceive.

Generally, the aim is to deliver the maximum amount of sperm to the entrance of the cervix. This means avoiding sex positions where sperm could leak from the vagina, for example while sitting or standing.

Some research also suggests that the contractions that accompany the female orgasm may help carry sperm further into the cervix, yet there is no known relationship between orgasm and fertility.²

^{1. Fertility: An Overview. A Guide for Patients. ASRM 2003; http://www.asrm.org/Patients/patientbooklets/infertility_overview.pdf}^{2. Optimizing Natural Fertility. Fertil Steril 2008;90:S1-6.}

Vagina

The muscular opening through which sperm travels in order to reach an egg. The vagina also serves as a passage for menstrual flow and secretions, which may assist or obstruct sperm in their journey to fertilizing an egg.

Varicocele

The presence of varicose veins around the testicles caused by poor circulation. The increase in blood leads to a rise in the temperature in the testicles. This causes abnormal testosterone levels, which hinder the production of sperm.

Vas deferens

A long curving tube that forms part of the sperm storage and transport system.

Manual palpation

A physical examination for any genital abnormalities or any other physical signs that might be associated with conception difficulties.

Myoma

A benign tumour in the uterus consisting of muscle tissue. Myomas are often the cause of persistent infertility or miscarriage.

Micromanipulation

A variety of techniques performed in a laboratory with microscopic guidance, such as Intracytoplasmic Sperm Injection (ICSI).

Menopause

Typically diagnosed 12 months after a woman’s last menstrual cycle. Natural menopause occurs when the ovaries begin decreasing their production of the sex hormones oestrogen and progesterone and marks the end of a woman’s fertility. See premature menopause.

Menstruation or menses

Shedding of the uterine lining by bleeding. In the absence of pregnancy, this normally occurs about once every 28 days.

Miscarriage

Spontaneous loss of a viable embryo or foetus from the uterus.

Motility

The ability of sperm to swim or move. Poor motility means sperm have less chance reaching and fertilizing the egg.

Multiple pregnancy

A pregnancy with two or more foetuses.

Mumps

A viral disease of the parotid (salivary) glands. Contraction of the virus after puberty may damage sperm-producing cells in the testicles. In most cases, only one testicle is affected. Some men could suffer permanent sterility.

Laparoscopy

Examination of the pelvic region by using a small telescope called a laparoscope.

Luteal phase

The days of the menstrual cycle following ovulation when progesterone is produced by the corpus luteum in preparation for embryo implantation.

Luteinizing Hormone

A pituitary hormone that stimulates the gonads. In a man, LH is necessary for the production of sperm and testosterone. In a woman, LH is necessary for the production of oestrogen.

Luteinizing Hormone Surge

The detection of increased luteinizing hormone (LH) levels indicates impending ovulation, i.e. a mature egg is about to be released from a follicle.

Cervical mucus

A natural lubricant produced by the female body that aids the transportation of sperm and helps protect against infection.

Cervix

The cervix or neck of the uterus is the lower, narrow portion of the uterus where it joins with the top end of the vagina.

Chlamydia

A sexually-transmitted infection, which may be asymptomatic or cause genital inflammation and discharge, pelvic pain and fever. Untreated, chlamydia can lead to Pelvic Inflammatory Disease (PID) and fertility problems.

Chromosomes

Structures found in the nucleus of cells that contain genes and carry heredity information, such as eye colour, blood type and vulnerability to disease. Humans have 23 pairs of chromosomes. One set of 23 chromosomes is inherited from the biological mother via her egg and the other from the biological father, via his sperm. Each sperm cell contains either male or female sex chromosomes. As such, it determines the gender of the foetus. Genetic abnormalities occur when an individual is born missing a chromosome or has more copies of a chromosomal pair.

Clomiphene citrate

A prescription drug used to bring on ovulation. It comes as a tablet and is often used as an initial treatment for women with ovulation problems. Clomiphene citrate induces ovulation in 80% of women who have trouble ovulating on their own.

Conception

The moment of fertilization when the sperm meets and penetrates the egg.

Congenital abnormalities

Physical abnormalities present at birth.

Corpus luteum

A hormone-secreting mass within the ovary that forms from the remains of a follicle each time an egg is released. The hormones it produces prepare the uterus for embryo implantation. If pregnancy does not occur, the mass is shed during menstruation.

Cryopreservation

A technique used to store human tissue at very low temperatures. Embryos that are not used in an ART cycle may be preserved in this way for future use. Also known as “Freezing”.

Cryptorchidism

A condition usually detected at birth or childhood whereby the testicles fail to descend. When a male foetus develops in the uterus, his testicles normally form inside his abdomen and descend into the scrotum shortly before birth. Undescended testicles usually descend themselves by the sixth month of life, but are unlikely to descend after this period of their own accord.

Basal body temperature

The lowest temperature attained by the body, usually measured immediately after awakening and before any physical activity is undertaken. A rise in body temperature of about half a degree about 14 days into an average 28-day cycle suggests ovulation has taken place.

Biopsy

The removal of a small portion of body tissue for microscopic examination.

Biosynthesis

A process where chemical compounds are made in the body from simpler compounds or smaller molecules.

Bladder

The organ that collects urine excreted by the kidneys prior to disposal by urination.

Blastocyst transfer

A procedure whereby an embryo is left to develop for about 5 or 6 days to reach the ‘blastocyst stage’ before being transferred into the uterus for implantation.

Obstetrician/Gynaecologist

A doctor who delivers babies and specialises in the treatment of female reproductive organs.

Oestrogen

A hormone that stimulates secondary female sexual characteristics and controls the course of the menstrual cycle. Oestrogen is also produced in low quantities in males.

Oligospermia

A condition when a sperm sample contains less than 20 million spermatozoa per ejaculate. Many medical conditions reduce sperm concentration. The effects may be temporary or permanent. See also Azoospermia.

Outpatient

A Person undergoing a clinical procedure that does not require admission to hospital.

Ovarian failure

The failure of the ovary to respond to hormonal stimulation from the pituitary gland because of damage to or malformation of the ovary, or a chronic disease such as autoimmune disease or ageing process.

Ovarian follicle

The structure in which eggs are nurtured to maturation. Although in general only one egg is released at a time, somewhere between 10 and 20 follicles begin the process of maturation monthly. The excess ovarian follicles are reabsorbed before ovulation occurs.

Ovulation

The release of the matured egg or ovum from the ovarian follicle.

Ovum

A matured egg.

Ovulation Induction (OI)

Medical treatment carried out to initiate ovulation.

Ovarian Hyper Stimulation Syndrome

A condition characterised by enlargement of the ovaries, fluid-retention and weight gain. May occur when the ovaries are over-stimulated during assisted reproduction.

Ovaries, Ovary

Almond-sized organ(s) located on either side of the uterus, which produce and release mature egg cells and the hormones oestrogen and progesterone.