Nishmat's Women’s Health and HalachaIn memory of Chaya Mirel bat R' Avraham

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Does norethisterone delay pregnancy?

14 March, 2005


I got married nearly 7months ago b”h. Before my wedding, I took norethisterone pills (Primolut Nor) for 3 weeks. I took 2-3 pills every day.

Before I got married my periods were quite regular, at a 5 week interval. My 1st period after we got married was after 47 days – naturally I thought I was pregnant. I took a pregnancy test and was utterly disappointed to see I was not. My next few periods were all at similar intervals.

I just got my period after 33 days which was quite a shock, but my husband pointed out that maybe the pills were in my system until now and 33 days used to be a normal length of time in between periods before I got married. Is it possible the norethisterone pill can delay pregnancy, as I did take quite a high dose? Thank you!


Mazal tov on your recent wedding!

The effects of Norethisterone can continue for a few months, potentially causing changes in the menstrual cycle. It does sound sounds as though the effects have now worn off, as you’ve returned to a roughly five-week interval.

It is normal for it to take up to one year for a young couple to conceive. If your cycle continues to be regular (around 5 weeks), you should consult your doctor if you do not become pregnant within a year. If you are over 35, or if your cycles revert to being very prolonged, or if you have other concerns, then you should consult sooner.

Down the road, you may also find it helpful to consult a Yoetzet Halacha Fertility Counselor. (This is a free service, details here.)

Please feel free to get back to us with any further questions.

This response was updated in October, 2020.

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