When referring to the period of time during pregnancy, the term "in utero" is commonly used. However, there are several synonyms that can be used to describe this time. Some of these synonyms include prenatally, gestationally, antenatally and embryonically. Each of these terms refers to the time before birth, while "in utero" specifically refers to the time the fetus is inside the uterus. These terms can be useful when discussing prenatal development, fetal health or complications during pregnancy. Using a variety of terms can also help to avoid repetition and make your writing more engaging.