Every week in my clinic I work with women desperate to conceive a child. Often they have had all kinds of gynaecological investigations and been told that everything is in perfect working order...and yet, still no baby.

For some of these women, the missing factor in the fertility equation is a little butterfly of tissue tucked away at the base of the neck – the thyroid. This tiny gland secretes thyroxin and other hormones responsible for regulating a myriad of body function including female hormonal balance, and consequently fertility.  

Thyroid function can go wrong in a number of different ways. Most commonly, the thyroid becomes either overactive (hyperthyroidism) or underactive (hypothyroidism).  Sometimes the body starts to shun its own thyroid, attacking it with antibodies.

An underactive thyroid can cause irregular periods, heavy bleeding and erratic ovulation. It is very possible to menstruate every month, and yet not be ovulating. No egg most definitely means no pregnancy. That’s why a couple of months of “do it yourself” ovulation kit testing is a great idea if you’re serious about conceiving. When the thyroid gland does not secrete enough thyroxin hormone (T4), treatment is necessary to bring hormone levels back to normal. This thyroid hormone controls the basic female hormones oestrogen and progesterone, which both play vital roles in fertility and maintaining a pregnancy.

Sometimes an underactive thyroid can cause another hormone called prolactin to become too high. This hormone is produced by a tiny gland in the brain called the pituitary, and is the same hormone responsible for the production of breast milk after childbirth. High prolactin can cause periods to stop altogether. Simple blood tests can show if prolactin levels are too high; or thyroid-stimulating-hormone is too high (this hormone elevates when your thyroid is sluggish and underfunctioning).

Hypothyroidism can also cause “luteal phase defect”. While it sounds like some kind of IT meltdown, it actually simply refers to a shortened second phase of the menstrual cycle.  In a healthy cycle, there should be at least 13 days from the time of ovulation until the start of the next period. It takes this long for a fertilised egg to find its way into the blood rich endometrium (lining of the uterus) and take a strong hold. Women who experience a shortened luteal phase are at a greater risk of suffering miscarriage very early on in pregnancy, as the fertilised egg fails to implant in the uterus.

Luteal phase problems are often the result of low levels of progesterone, sometimes caused by an underactive thyroid. Progesterone deficiency inhibits the thickening of the lining of the uterus, which in turn prevents the embryo from attaching. With this problem, a woman may not even know that she was pregnant, miscarrying when her next period is due.  

An overactive thyroid can also stand between you and a beautiful baby. In fact, even a slight degree of overactivity can result in either infertility or repeated miscarriage, even when your periods appear normal, healthy and regular. Once again, it’s just a simple blood test to find an overactive thyroid...that, and likely symptoms of anxiety, hyperactivity, racing heart and unexplained weight loss.

While you’re having your thyroid tested, make sure the doctor checks for thyroid antibodies at the same time – many doctors still do not know of the link between these and infertility. The Journal of Obstetrics and Gynaecology reported that the presence of thyroid antibodies increases the risk of miscarriage.

Thyroid antibodies can also reduce the likelihood of successful IVF treatment, regardless of whether or not there are any symptoms of an underactive thyroid. Treating with heparin (an anti blood clotting agent) and aspirin seems to increase the success of IVF treatments in patients with thyroid antibodies.

So, if you’re trying unsuccessfully to conceive, make sure that one of your first investigations is a thorough thyroid examination and blood tests.

Lynda@lyndawharton.com

www.lyndawharton.com