Understanding Pregnancy Loss in the Context of Abortion Restrictions and Fetal Harm Laws

Appendix A: Brief Timeline of Cardiac Development
Gestational Age (GA) Description
~5 weeks GA The embryo’s developing heart is tubular in shape, and called a primitive heart tube. At this time, this collection of cells develops spontaneous cardiac activity, typically detectable after 6 weeks gestational age.
~10 weeks GA The heart’s shape now resembles a developed heart with four chambers. It does not yet function as a developed heart.
~22 weeks GA The heart beings to function as an organized muscle. The direction and function of fetal blood flow is still very different from that of a newborn’s.
At delivery  The cardiovascular system of the fetus goes through a dramatic series of structural and functional changes.The newborn’s heart, lungs and blood flow only now resembles that of a child or an adult.
NOTES: Most research on the topic of human development/embryology will discuss timelines in terms of embryonic/fertilization age (time since fertilization). For consistency, however, we refer to all points in pregnancy by the gestational age (time since last menstrual period). There is approximately a two week difference between gestational age and fertilization age, and different sources may use different units of measurement.
Appendix B: Multiple Terms Are Used To Describe Pregnancy Loss And Early Infant Death
<13 weeks GA 13-20 weeks GA 20 weeks GA to delivery After Delivery
Early pregnancy loss Early second trimester pregnancy loss

Stillbirth*
Fetal death/demise
Intrauterine fetal death/demise (IUFD)

Neonatal death  (<28 days old)
Infant death (<1 year old)

Spontaneous abortion
Miscarriage (as used in medicine)

Miscarriage (as used in lay press and policy)
NOTES: GA = gestational age, calculated as time since the first day of the last menstrual period (LMP). *In clinical practice, stillbirth may refer to pregnancy loss after 28 weeks rather than 20 weeks depending on the practice setting. A late IUFD refers to pregnancy loss after 28 weeks.
SOURCES: ACOG Practice Bulletins: Early Pregnancy Loss and Stillbirth; UpToDate articles: Miscarriage and Stillbirth
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