Why is Caffeine Bad for Pregnancy?

Part 2 in a 3 Part Series on the Impact of Caffeine on Reproductive Health

By Paul J.O'Brien
B.A., N.C.E.H.S., Dip. Acu., Cert Clin. Med., Pn1, PN-SSR, PN-NCA, M.T.C.M.C.I., M.C.Th.A.

Why is Caffeine Bad for Pregnancy is the 2nd part in a detailed 3 part series exploring the risks of caffeine to our reproductive health. In Part 1: Why if Caffeine Bad for Fertility, I introduced some of the hidden sources of caffeine outside of coffee itself and explored some of the risk and the quantities those risk occur at for both men and women. 

The results are shocking. 

Essentially in varying quantities, caffeine can lead to;

A 70% increase in estrogen, linked to endometriosis and other reproductive health issues, including infertility. 

  • A reduction in uterine blood flow, thinner lining, reduced risk of implantation
  • Poor egg quality
  • Poor egg maturation
  • Compromised iron absorption leading to reproductive and ovulation disorders including secondary infertility
  • Reduction in sperm motility

For more detail and the studies referenced in that series you can read the full article - here

In this article I want to focus on the impact of coffee if you've already conceived...and in part 3, I'll tell you what you can do about it. 

Why is Caffeine Bad for Pregnancy? - Increased Risk of Miscarriage.

In Part 1 I touched on three aspects of how caffeine affects live birth rates; firstly by decreasing blood supply; secondly through a reduction in Iron Absorption and thirdly by mutating sperm.  Another aspect of caffeine I didn't discuss in the previous article is that it is diuretic in nature, meaning we pass more urine than normal. Excess urination, something that will be happening anyway as a result of pregnancy, and will only be increased by caffeine consumption can flush out important nutrients that are essential for the reproductive system to function optimally.

However there's even more evidence. 

A study published in the Journal of Obstetrics and Gynaecology, January 21, 2008 by Dr De-Kun Li, a reproductive perinatal epidemiologist at the Kasser Permenente Division of Research in Oakland (California U.S.) analysed the effect of caffeine consumption on 1,063 pregnant women. The results were markedly negative. 

Essentially the study showed that by drinking 200mg or more of caffeine per day (1-1.5 cups of tea per day) they had double the risk of miscarriage in compassion to women who had consumed no caffeine.  

To put that in perspective, those women who consumed no caffeine had a miscarriage rate of 12.5%. Those who had consumed 200mg plus of caffeine per day had a miscarriage rate of 24.5%. That means about one in four women who have more than 1 cup of coffee a day could have a miscarriage. 

Additional studies have shown the greater consumption of caffeine the higher the risk of miscarriage.  They also looked at the evidence prior to conceiving, and though we know from Part 1 that caffeine has a negative impact on pregnancy, it seems that more than 3 cups of coffee per day taken in the month before pregnancy also carries with it a greatly increased risk of miscarriage.  

A study in Denmark found that the risk of stillbirth more than doubled in women who drank eight or more cups of coffee each day compared with women who didn't drink coffee. 

Caffeine also has been shown to be linked to low weight babies and an increase in still birth

A Norwegian  study of nearly 60,000 women concluded that coffee and other caffeinated beverages increased the odds of delivering a low birth weight baby and/or extended the gestation period quite dramatically. In fact the figures show that for every 100 mg of caffeine consumed by the mother per day leads to a nearly one ounce reduction in the baby's weight at birth and simultaneously increases the length of the pregnancy by about 5 hours...though if taken straight from coffee a 100mg dose extends pregnancy by 8 hours.   

Dr. Jennifer Wu, of that study said,

"We do know that caffeine crosses the placenta and the baby is not able to metabolize it very well, [so] it may affect some of the factors associated with growth"

She advised that women limit the amount of caffeine they consume during pregnancy.

According to Gerald Weissman, M.D. and editor-in-chief of the FASEB Journal:6 

"Caffeine is everywhere: in what we drink, in what we eat, in pills that we use to relieve pain, and even in candy... This report shows that despite popular notions of safety, there's one place it probably shouldn't be: in the diet of an expectant mother."

One final consideration - As pregnancy progresses your body's ability to break down caffeine slows, As such you will have higher levels of caffeine in your bloodstream. In the 2nd trimester it takes almost twice as long to clear caffeine from your body as when you're not pregnant. During the third trimester, it nearly takes three times as long.

Meanwhile the caffeine in your blood is passing through the placenta and being taken up in the babies blood supply, and the baby can't process this well at all. This also contributes to low birth weight and studies have demonstrated that newborns whose mother consumed more than 500 mg of caffeine a day had faster heart rates and breathing rates and spent more time awake in the first few days after birth.

Let me make this very clear - ingesting even a small amount of caffeine can have devastating affects on your ability to conceive and maintain the pregnancy.  

So what can you do about this? Give up your coffee and caffeine immediately? No, that could lead to great stress and cortisol release in the body. Going through a tough withdrawal (covered in Part 1) is not ideal when actively trying to conceive and certainly not when pregnant. 

So what do you do - I have a solution in Part 3.  

In the meantime, if you are planning on starting a family, or have had problems with conception and maintaining a pregnancy in the past then please feel free to contact me and I'll do my best to help. 


  • http://www.biomedcentral.com/1741-7015/11/42/abstract
  • Christopher C. Wendler, Melissa Busovsky-McNeal, Satish Ghatpande, April Kalinowski, Kerry S. Russell, and Scott A. Rivkees. Embryonic caffeine exposure induces adverse effects in adulthood . FASEB J. first published on December 16, 2008 as doi:10.1096/fj.08-124941.

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You've been reading Why is Caffeine Bad for Pregnancy? Read about the TCM understanding of coffee in my published article on the 'benefits' of coffee here

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