The fertility drug Clomid (clomifene) has been prescribed by doctors for decades as a first-line of treatment for women who have irregular or absent menstrual cycles. It is also routinely prescribed for women who ovulate normally but have otherwise unexplained infertility.

However, a plethora of Clomid birth defects have been reported, including congenital heart lesions, Down Syndrome, club foot, congenital gut lesions, hypospadias, microcephaly, harelip and cleft palate, congenital hip, hemangioma, undescended testicles, polydactyly, conjoined twins and teratomatous malformation, patent ductus arteriosus, amaurosis, arteriovenous fistula, inguinal hernia, umbilical hernia, syndactyly, pectus excavatum, myopathy, dermoid cyst of scalp, omphalocele, spina bifida occulta, ichthyosis and persistent lingual frenulum.

There have also been some reports of neonatal deaths and stillbirths in infants with birth defects whose mothers took Clomid.

Clomid hit the market in the 1960s, initially to treat women who had irregular menstrual periods, a condition known as oligomenorrhea. Clomid treatment late expanded to include treatment of anovulation, when women have a period but their ovaries don’t release an egg cell required for reproduction. It was during the anovulation treatment that the medical community realized women undergoing treatment experienced higher than expected rates of pregnancy.

In 1989, Yale University Medical researchers were awarded a patent for the use of clomiphene to predict female fertility.

Clomid works as an ovary stimulant. It induces ovulation in women trying to become pregnant, but who have irregular menstrual cycles, particularly those with polycystic ovarian syndrome.

In 2010, the Oxford Journal on Human Reproduction reported that 1.6 percent of pregnancies in the United States are conceived with the use of clomiphene citrate drugs such as Clomid and Serophene. That figure translates to some 67,000 exposed pregnancies per year.

The Oxford Journal on Human Reproduction reported in 2010 that some 1.6 percent of U.S. pregnancies are conceived with the use of clomiphene citrate drugs such as Clomid and Serophene, translating to approximately 67,000 exposed pregnancies per year.

While Clomid can stimulate ovulation, it remains in the mother’s system during the early weeks of pregnancy, exposing the fetus to its dangerous side effects.

Clomid is classified by the FDA as a Category X drug, which means it is known to cause birth defects and animals or humans have developed fetal abnormalities in clinical research. The testing is typically performed on animals since it is too risky to perform on humans. If a birth defect is present in animals exposed to a certain medication, it is usually assumed it will also pose a risk in humans.

Category X drugs’ risks may outweigh the potential benefits and should be carefully discussed with a doctor before using.

Two types of Clomid birth defects commonly reported in studies were neural tube defects and hypospadias, when the urinary opening in a baby boy is not on the head of the penis, though the association between clomiphene citrate drugs and these birth defects have been inconsistent.