L-Arginine in pregnancy: know your supplements

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L-Arginine is included in many formulas for improving egg health. Will L-Arginine in pregnancy help you?

What does the science say? There are 2 main studies on L-Arginine for improving female fertility.

Will L-Arginine help in pregnancy?

There is one study done on women taking L-Arginine as a supplement to improve fertility outcomes. L-Arginine was one of many ingredients in a proprietary nutritional supplement by the Daily Wellness Company called FertilityBlend.

30 women from the age 24 – 46 years were split into two groups.

15 provided with FertilityBlend, the other with a placebo. At the end of 5 months 4 women were pregnant in the FertilityBlend group, none in the placebo group.

This sounds promising, right?

You could presume from this study that any woman from the age of 24 – 46 years of age has a 30% chance of falling pregnant using this product. But that is not the case.

15 women tested for taking the product is too small a sample size for any real statistics. L-Arginine was included amongst Vitamin E, B6, B12, Folate, Iron, Magnesium, Zinc, Selenium, Green Tea and Chasteberry. It has never been tested on its own for results. There were no pre-existing fertility problems recorded for any of these women and success rates in the different ages of women not reported.

So how did L-Arginine gained popularity for a supplement to assist with women’s fertility and improve egg quality and low ovarian reserve.

A much better study was performed in 1999. It only had 34 women in the study, and only 3 of them fell pregnant. What it showed is that women who were poor responders to IVF Gonadotrophin and Follicular Stimulating Hormone drugs could benefit from L-Arginine. They discovered that taking L-Arginine with the IVF drugs made the drugs work better and women produced more follicles than before.

Unfortunately the study is old now, and IVF doctors do not supplement their clients with L-Arginine in pregnancy. 19 years later, upon reflection science has concluded that

there is inconsistent evidence about the effectiveness of L-arginine for infertility. Some early research suggests that taking 16 grams of L-arginine daily increases egg counts collected in women undergoing IVF. However, it does not seem to improve pregnancy rates.

It does appear to help men with low sperm motility, but that is it as far as science and fertility goes.


We are disappointed we were unable to come up with any evidence of claims that L-Arginine promotes fertility in women. Websites and products that suggest that L-Arginine helps women with infertility reference studies and clinical evidence that do not support good science or current thinking.

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