Fetal Development & Stress

These flashcards cover essential vocabulary and concepts related to the effects of maternal stress on fetal development.

Barker’s Hypothesis

The idea that conditions in the womb (stress, undernutrition) can “program” long-term adult disease risk like heart disease, diabetes, and hypertension.

Programming Hypothesis

Non-genetic factors such as hormones or stress can permanently alter fetal organ and physiological system development.

How different trimesters of pregnancy vary in sensitivity to stress

• 1st Trimester (0–12 weeks): Organ formation → stress can cause structural defects or malformations.

• 2nd Trimester (13–28 weeks): Rapid brain and nervous-system growth → cognitive, attention, and behavioral issues.

• 3rd Trimester (29–40 weeks): Final growth and maturation → preterm labor, emotional-regulation problems.

main adverse outcomes of maternal stress

IUGR (small baby), low birth weight (<2500g), preterm birth (<37 weeks), altered brain development, behavioral/emotional issues.

11β-HSD

An enzyme produced by the placenta that regulates cortisol levels, converting active cortisol to inactive cortisone. reducing fetal exposure 

Glucocorticoids

Stress hormones that aid in fetal development, but can be harmful in excess.

IUGR (Intrauterine Growth Restriction)

A condition where fetal weight is below the 10th percentile for age.

Low Birth Weight (LBW)

Refers to infants weighing less than 2500 grams at birth.

Preterm Birth

Birth that occurs at less than 37 weeks gestation.

Critical Period

A phase during development when systems are most vulnerable to disruption.

Teratogen

Any environmental factor, such as stress or drugs, that disrupts fetal development.Early exposure = structural defects; later exposure = functional/behavioral issues.

Cumulative Stress

The combined effect of chronic and acute stress sources on maternal and fetal health.

Pregnancy-Specific Anxiety

Anxiety specifically related to pregnancy and childbirth.associated with shorter gestation and emotional regulation problems in infants.

Neurodevelopmental issues

Problems related to learning, emotion regulation, and increased risk for ADHD due to fetal stress exposure.

Cortisol

The main stress hormone that crosses the placenta and influences fetal brain development.

FETAL DEVELOPMENT & STRESS

How maternal stress during pregnancy affects fetal growth, brain development, and long-term health (through biological and hormonal pathways (especially the HPA axis).

HPA axis

the hypothalamic-pituitary-adrenal (hpa) axis, the body's central stress response system that consists of the hypothalamus, the pituitary gland, and the adrenal glands.

What system mediates maternal–fetal stress communication?

The HPA Axis (Hypothalamus → Pituitary → Adrenal glands).

What is the placenta’s role in fetal stress protection?

It produces 11β-HSD, which converts active cortisol to inactive cortisone, reducing fetal exposure.

Which hormone can cross the placenta and influence fetal development?

cortisol

Which brain regions are most affected by prenatal cortisol exposure?

The amygdala and hippocampus — linked to emotion and learning regulation.

What is the function of glucocorticoids during pregnancy?

Support organ maturation (lungs, pancreas, cardiovascular system) and prepare the fetus for birth — but excessive levels can harm brain/metabolism.

: What defines a preterm birth?

Birth occurring before 37 weeks of gestation.

How does maternal stress biologically affect the fetus?

Increases CRH → ACTH → Cortisol → crosses placenta → alters fetal heart rate, brain development, and stress regulation.