The standard advice given to all women taking Carisoprodol is they should seek medical advice if they become pregnant or wish to use the drug while breast-feeding. The reason for the Category C warning is evidence from animal testing. Testing drugs on animals is a necessary precaution before allowing humans to take any substance. Some animals have biology sufficiently close to ours that we can quickly see whether there are likely to be problems. In the case of this drug, there are two sets of findings. The first concerns female animals. There's clear evidence the drug crosses the placenta barrier and enters the fetus. In smaller animals, this affected the rate at which the fetuses grew and there was an increase in infant mortality. For male animals, there's some evidence of a reduction in the size of testes and a slight fall in the volume of sperm. In human testing, there's also clear evidence that Carisoprodol passes into breast milk and so is consumed by your baby.
The allocation of this drug to Category C by the FDA is a value judgement that the benefits of the drug outweigh any possible danger to the human fetus. There are no recorded cases of damage to human male sexual reproduction. So what has the postmarketing reporting shown for women? The answers are fairly encouraging. For example, the Medical Center at Long Beach, CA described a young woman who took a high dose of the drug during pregnancy and while breast-feeding for the first month after birth. Regular blood samples were taken throughout and, despite clear evidence that the active chemicals were present in both the fetus and the baby when born, there were no adverse effects. The baby was born with an average weight, did not experience withdrawal symptoms, and remained healthy during breast-feeding and afterwards. This is one of some sixteen published reports that shows no adverse effects on the child's development, even when the mother is taking a high dose. Although none of the studies have been long term, there seems to be little risk to either mother or child in taking Carisoprodol during or immediately after pregnancy.