It is true that thyroid problems can sometimes be an impediment to getting pregnant. With no egg to fertilize, conception becomes impossible. In addition, some women experience a short luteal phase. The luteal phase is the timeframe between ovulation and onset of menstruation. For example, Dr. Rubenfeld said that hypothyroidism can cause an increase in prolactin, the hormone produced by the pituitary gland that induces and maintains the production of breast milk in a post-partum woman.
Excess prolactin has a negative effect on fertility.
In addition, Dr. Rubenfeld said that while there have been few systematic studies of this, there is clear evidence that hyperthyroidism can affect fertility by causing a low sperm count or reduced sperm motility in men. This condition is, however, treatable. Some women are concerned that a husband or partner's thyroid problems will interfere with the ability to sustain a pregnancy. Again, according to Dr. Rubenfeld, evidence exists that some men with hyperthyroid may have a lower sperm count or sperm motility than normal. However, if the woman becomes pregnant, there is no concern that her partner's thyroid disease will affect her pregnancy.