Fasting While Pregnant?

Read time: 2 minutes

Recently reader Brianne asks if I’ve ever seen information on fasting and pregnant women.

I explored this area not too long ago and found some interesting studies on pregnant women and fasting. I’ll present them in a moment. First I want to mention:

Many pregnant women do in fact practice fasting. Ramadan and Yom Kippur are religious observations in which healthy pregnant women fast. However, there are general fasting flexibility within each of these religions for the pregnant woman.

During Ramadan, if a pregnant woman fears for her health or the health of  the unborn child, then she can fast the same equivalent of days at another time or feed the poor to compensate.

During Yom Kippur, if a pregnant woman feels dizziness or nausea, she may eat in “measures,” which means only a small amount of food and a cheekful of water.

In both religious observations, however, the healthy pregnant woman is encouraged to endure through the fast. This is serious religious practice. 

The point I’m showing is that pregnant women have been fasting for a long time. But does it mean it’s the safest thing to do?

I looked at some studies (note: mostly abstracts). Here is what I’ve found. 

One study shows that, in 110 pregnant women in their third trimester, short-term fasting of 12 hours has no effect on uterine and umbilical indices, or fetal cerebral artery developmental status (Abd-El-Aal, 2009).

Another study concludes that Ramadan maternal fasting has no effect on the birth weights of 13,351 babies born at full term (Cross, 1990).

Another study of healthy pregnant women found no difference between the fasting group (n=39) and control group (n=29) for fetal age, maternal weight gain, estimated fetal weight gain, fetal biophysical profile, amniotic fluid index, and umbilical artery blood pressure. In the fasting group, HDL (good cholesterol) increased slightly, and LDL/HDL ratios were significantly decreased (Dikensoy, 2009).

Another study concludes that fasting during Ramadan does not lead to excessive ketones in the body or urine of pregnant women. Additionally, fasting during Ramadan has no significant adverse effect on intrauterine fetal development or the fetus’s health (Dikensoy, 2008).

So do I recommend fasting to pregnant female? I’ll say no. Not everything is always simple: these studies examined healthy women with low-risk pregnancies. The whole story can change in pregnant women with diabetes, thyroid dysfunction, Cushing’s syndrome, adrenal disease, pre-eclampsia, and multiple pregnancy (twins, etc).

But I will tell you this: fasting in pregnant women isn’t new. This has been going on throughout history in observation of religious beliefs. Additionally, hunter-gatherers may have lived through irregular eating patterns, even if within a tribe the pregnant female garnered dietary support from others. We ought to remember the brilliance of the human body to adapt to feed patterns.

Archives of Disease in Childhood
Archives of gynecology and obstetrics
International Journal of Gynaecology and Obstetrics
The Journal of Obstetrics and Gynaecology Research
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5 Responses to Fasting While Pregnant?

  1. Thanks. People are scared of fasting.

  2. brianne says:

    THANK YOU, Johnny. I agree that for healthy women, the practice is probably safe. I tend to always skip breakfast (except for coffee w/heavy whipping cream…which I’ll continue while pregnant :)) and a few days a week also “skip” lunch…so I’m not overly concerned. I appreciate you taking the time to post on this topic!

  3. Kat Eden says:

    Interesting. What do you think about fasting and breastfeeding, or even a 2-3 day juice/veg detox and breastfeeding?

    • Johnny says:

      Hi Kat,

      The classical concern about fasting and breastfeeding is whether fasting affects the volume of milk. The other concern is the composition of milk.

      It seems that, in short-term fasting, milk volume is not affected if hydration is maintained — the fasting mother should drink adequate water. So short-term fasting doesn’t seem to affect milk volume.

      Under short-term fasting, it appears the body naturally finds ways to meet the need of breast milk production. Apparently, as long as hydration is adequate, milk volume and composition are maintained.

      Consider the many substandard conditions throughout history (and in modern times) when a mother did not experience what we today consider an ideal condition for breastfeeding, yet the development of off springs was complete and full.

      But as much as it sounds like I see no issue with fasting while breastfeeding, I still cannot recommend this combination where it’s not needed. First, you have one chance to optimize the development of the child, and who knows how fasting truly affects the profile and composition of breast milk. Second, fasting stimulates greater fat release, which may liberate any toxin stored inside fat tissue — although I’ve never seen information on this, I’d hate to think that the mother is passing this toxin to her baby.


  4. Kat Eden says:

    True – and good point. Thanks for getting back to me.

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