2.11.2. Untoward effect of green tea

Pregnant women who consumed green tea are at risk of spontaneous abortion as shown by the following two studies. A case control study conducted on 3149 pregnant women showed that serum paraxanthine (caffeine metabolite) was higher in women who had spontaneous abortions than in controls [62]. Another case control study conducted on 1498 pregnant women also showed that consumption of 375 mg or more caffeine per day during pregnancy might increase the risk of spontaneous abortion [63]. Pregnant women who consumed high caffeine during pregnancy have a chance to deliver low birth weight infants. This is supported by the following studies. A prospective study conducted on 2291 pregnant women reported that women who consumed more than 600 mg of caffeine per day are at greater risk for having low birth weight infants [64]. A prospective study conducted on 63 women also reported that pregnant women who consumed more than 300 mg/day of caffeine had low birth weight newborns [65]. Studies showed consumption of high doses of caffeine had increased risk of stillbirth. A prospective follow-up conducted on 18,478 singleton pregnancies showed that the consumption of eight or more cups of coffee in a day doubled the risk of having stillbirth compared with women who did not consume coffee [66].

Even though the above studies are conducted on coffee consumption, consumption of high doses of green tea can have adverse effects on mothers and their infants. Caffeine found in coffee and green tea is not very different. Consumption of too much caffeine (more than 300 mg per day or more than eight cups per day) can cause miscarriage as seen by the above research findings. Consumption of too much caffeine can also cause trouble of sleeping.
