Fosamax During Pregnancy & Breastfeeding

by on April 22, 2012


Fosamax has been assigned by the FDA to pregnancy category C and the manufacturer recommend that this medication be prescribed during pregnancy only if the perceived benefits outweigh the potential risks. Animal studies in rats have shown evidence of maternal toxicity, protracted parturition, and incomplete fetal ossification in doses 1 to 9 times the size of the human dose.  Rabbits that were treated at doses 50 times greater than the human dose did not see the same effects. Since controlled data in human pregnancy does not exist, it is only recommended that Fosamax be used if there are no alternatives.

Can Pregnant Women Take Fosamax?

Biphosphonates, including Fosamax, become part of the bone. However, these compounds are released from the bone into the systemic circulation over a period of time. Fosamax increases the amount of biphosphonates in the body, and hence, the amount that will gradually be released is likely to be higher than normal. Its potential effects on the developing fetus are not clear but theoretically, there is an increased risk for fetal harm. Skeletal anomalies are more likely in patients who have become pregnant after completing a Fosamax treatment. There are no studies on the possible effects of variables such as duration of treatment, dosage of medication and route of administration.

Animal studies suggest that exposure to Fosamax increases the risk for miscarriages and giving birth to an infant that weigh lower than normal. In addition, animal studies further suggest problems with fetal bone formation and development. Some of the most common sites of skeletal problems include backbone, skull and sternal bones. Furthermore, these studies suggest that biophosphonates can considerably decrease blood calcium levels which can cause delays and failures of delivery.

Take note, however, that these animal studies do not definitely predict the response of pregnant women on the medication. As such, it possible for your healthcare provider to prescribe this medication if the perceived benefits are greater than the risks.

Fortunately though, since Fosamax is a medication used to prevent or treat osteoporosis common in post-menopausal women, use of this medication in pregnant women is rather unlikely.

Can Breastfeeding Patients Take Fosamax?

Before you start taking Fosamax, be sure to inform your healthcare provider if you are breastfeeding or plan to breastfeed. No studies have been done to determine if this medication is excreted into the human breast milk. As such, it is not known whether or not Fosamax can be passed through the breast milk.

Fosamax becomes integrated in the bones and gradually released from it. Women who have completed a course of Fosamax treatment may have higher levels of this medication. There is not enough data to see how such increase can affect the breast milk produced as well as the growing bones of the nursing infant.

Because of the inadequate studies and the potential risks of this medication, many healthcare providers do not recommend this medication for breastfeeding women.

Consult your healthcare provider about breastfeeding and Fosamax. Each patient has a unique condition, and your healthcare provider is in the best position to give you appropriate advice.