umls-concept:C0000768 | skos:definition | MSH: Malformations of organs or body parts during development in utero.,MEDLINEPLUS: <p>A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of pregnancy. One out of every 33 babies in the United States is born with a birth defect.</p><p>A birth defect may affect how the body looks, works or both. Some birth defects like <a href='http://www.nlm.nih.gov/medlineplus/cleftlipandpalate.html'>cleft lip</a> or <a href='http://www.nlm.nih.gov/medlineplus/neuraltubedefects.html'>neural tube defects</a> are structural problems that can be easy to see. To find others, like <a href='http://www.nlm.nih.gov/medlineplus/congenitalheartdefects.html'>heart defects</a>, doctors use special tests. Birth defects can vary from mild to severe. Some result from exposures to medicines or chemicals. For example, alcohol abuse can cause <a href='http://www.nlm.nih.gov/medlineplus/fetalalcoholsyndrome.html'>fetal alcohol syndrome</a>. <a href='htt | lld:umls |