When in a pregnancy are birth defects most likely to happen? the first trimester the second trimester the third trimester equally likely in all trimesters

During the "first trimester of pregnancy" birth defects are most likely to happen.

Option A

Explanation:

Birth defects can develop during any pregnancy stage. But the majority of birth defects occur during the first 3 months of pregnancy, when the baby's organs develop as it is very important phase for development. The body's biggest structures shape during the first trimester. These include the thighs, head, arms and the spine.

Factors which may lead to a birth defect or increase its chances include genetics, socio-demographic factors, drugs and alcohol, environmental factors , vaccine preventable infections, inadequate nutrition, pre-gestational diabetes, obesity, diet and fertility treatments.

Testing during pregnancy, particularly for women at greatest risk, can aid in diagnosing birth defects before birth like combined first trimester screening (CFTS), non-invasive prenatal testing (NIPT), ultrasound, amniocentesis, percutaneous and chorionic villus sampling (CVS).