Why does an irregular cycle make it harder to get pregnant?


An egg and sperm meeting is central for a pregnancy to take place and for it to happen, ovulation is required. As we described above, ovulation is dependent on several events and hormones that need to be balanced. If not working properly, it can lead to completely absent ovulation or irregular ovulation, which in turn leads to a or irregular period. Without ovulation, it is impossible to get pregnant and if ovulation rarely occurs, the number of chances you have will decrease. Irregularities can also make it more difficult to identify when your ovulation is coming and thus schedule sex in connection with it.

Luteal phase

Getting an egg fertilized is not all it takes to get pregnant. As we described above, the fertilized egg (embryo) also needs to attach to the uterine lining and develop there – the first time is critical. This requires that the uterine lining is receptive, has the right thickness, and so on, and the hormones estrogen and progesterone ensure this. Progesterone is secreted by the collapsed ovary and if it does not secrete enough or long enough, the uterine lining collapses "prematurely"; you get your period "too early". By "too early" we mean that the embryo does not get the time it needs to be able to attach and this is the reason why you want this part of the cycle to be at least 11 days long.


Evangelia Elenis, MD, PhD.

This text is fact checked by Evangelia Elenis, MD, PhD. Dr. Elenis is a chief physician in Obstetrics and Gynecology, and a subspecialist in Reproductive Medicine. She is a PhD and affiliated researcher at Uppsala University with postdoctoral studies at Harvard Medical School.

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