Module 4 Lesson 3 - 4

Reflect on the Big Picture

The discovery of pregnancy when a couple wants children is exciting and awesome. However, many expectant couples choose to wait until the pregnancy is at least three months along (the end of the first trimester) before they announce the news. This corresponds to the completion of embryonic development and the first months of fetal development.

Most miscarriages happen within the first 13 weeks of a pregnancy, and most of miscarriages are due to chromosomal abnormalities that prevent normal embryonic and fetal development. Therefore, many couples wait to inform their friends and family they are pregnant until this time period has passed.

Lesson Summary

Prenatal development is divided into three trimesters and two development periods. Embryonic development begins at fertilization and ends after about the eighth week of pregnancy. Fetal development begins at the ninth week and continues until birth. Both embryonic and fetal developments occur within the first trimester. The first trimester is the time when the developing embryo and fetus is most vulnerable to improper nutritional requirements and exposure to harmful teratogenic agents because this is when the most sensitive embryonic development occurs. The fetal period consists of significant development events related to the progressing months of pregnancy. Most of the time spent in the fetal period results in further development of the organ systems. The understanding of the 'significant developmental events during pregnancy helps doctors and parents to follow the development of maturing fetus to term (completion and birth).