Hi, Thanks fort the query. Ampicillin is a category B drug meaning that as such no adverse effects have been found in humans but actual studies have not been conducted. This is typical of many drugs as it is against ethics to test drugs on pregnant women. My own experience has found it very safe. Unfortunately clarithromycin is a category C drug, meaning that studies in animals have shown fetal abnormalities with high drug doses and there are no well controlled studies in humans. However available data has shown that it does increase the chance of congenital abnormalities slightly more than that expected in the general population. It is to be used when the need is absolute and the risk to the mother is more if it is not used; example life threatening infection etc. Omeprazole also falls under category C and few anomalies have been noted with this. So the chances of anomalies are slightly more than the general population. However our daily experience shows that the risks are just slightly increased than the risk when there is no drug exposure. Meaning that every pregnancy carries a risk of 2-3% of having an anomaly. With these drugs it may be slightly more. risk reduction may be done by prenatal testing for chromosomal anomalies by chorionic villus or amniocentesis samples. Gross anomalies can be detected using level 4 ultrasound. So I suggest that you consider all these issues and decide about the future course of action. Hope this satisfies your query. Thanks for using HCM. Feel free to ask any more questions that you may have. Dr Madhuri Bagde Consultant Obstetrician and Gynecologist