Methods in Prenatal Development

Longitudinal Design

A research method where data is collected from the same group of participants over a prolonged period of time (e.g., testing the same children at 12, 18, 24, and 30 months).

Cross-Sectional Design

A research method where data is collected from different groups of participants at different ages at the same time (e.g., comparing a group of 12-month-olds to a group of 30-month-olds).

Microgenetic Design

A developmental design focused on capturing change as it occurs over very short periods of time.

Developmental Designs Goal

To capture and understand how individuals change over time.

Study: Awe and Donating Behavior

Children in the "Awe" condition were significantly more likely to donate their treats compared to those in the "Joy" or "Control" conditions.

Study: Pets and General Anxiety (GA)

A lower percentage of children with pets met the clinical cut-off for General Anxiety compared to children with no pets. Caution: While a correlation exists, researchers must determine if the study was a true experiment before claiming a causal link.

Study: The Bystander Effect in Children

Do children exhibit the bystander effect (the tendency to be less likely to help when others are present)?

Study: The Bystander Effect in Children Conditions

• Alone: Child is by themselves.

• Bystander: Child is with others who can help.

• Bystander-Unavailable: Child is with others who are physically "fenced in" and cannot help.

Study: The Bystander Effect in Children Stimulus/Variables

An experimenter spills water and needs paper towels, progressing from a groaned "Oops" to a direct request for help over 90 seconds.

1. Help vs. Didn't Help; 2. Quickness of helping.

Study: The Bystander Effect in Children results

Children were significantly less likely to help in the "Bystander" condition (~55% helped) compared to the "Alone" or "Bystander-Unavailable" conditions (>90% helped)

Gametes

Reproductive cells (sperm and ovum) that each carry 1/2 of the genetic material (23 chromosomes)

Ovum (Egg)

One of the largest cells in the human body. It has a brief viability period of about 24 hours and is available in a limited supply

Sperm

Considerably smaller than the ovum, sperm can survive for about 6 days in the female reproductive tract. They are created continuously (~2 trillion per lifetime).

Ovulation

The process where follicles mature and one egg is selected to travel through the fallopian tube to the uterus.

Dizygotic Twins

Also known as fraternal twins; they occur when two separate eggs are fertilized. They are no more genetically alike than ordinary siblings (31 in 1,000 births in the U.S.).

Fraternal Twin Predisposing Factors

Factors including fertility treatments, ethnicity, family history, maternal age, body build, and potentially diet.

Conception Challenges (Sperm Failure)

Of 300 million sperm, only about 200 reach the egg due to: choosing the wrong fallopian tube, being attacked by the female immune system, an inhospitable environment, or genetic defect

The Active Ovum

The egg actively assists conception by emitting a chemical beacon to attract sperm and creating a chemical seal to prevent multiple fertilizations once one sperm enters

Trisomy 21 (Down Syndrome)

A condition characterized by an extra 21st chromosome, resulting in cognitive impairment, health concerns, and distinct facial features.

Maternal Age and Down Syndrome Risk

The risk of Trisomy 21 increases exponentially with age:

Age 20-30: ~0.1% risk.

Age 40: 0.8% risk.

Age 45: 3.6% risk.

Advanced Paternal Age

increased father's age is associated with mixed evidence on fertility but a known relationship with certain developmental disorders in offspring.

Amnion

The inner membrane that forms a protective, fluid-filled sac around the fetus.

Chorion

The outer membrane that surrounds the amnion and helps form the placenta.

Placenta

The organ that provides oxygen and nutrients to the developing baby and removes waste products from the baby's blood.

Umbilical Cord

The tube connecting the fetus to the placenta.

Amniotic Fluid

The fluid within the amnion that cushions the fetus and helps maintain a steady temperature.

Trimesters

The division of prenatal development into three periods of equal length (approximately 3 months each).

Germinal Stage

The first stage of prenatal development, lasting from conception to implantation (Week 2). During this time, the zygote travels to the uterus and burrows into the uterine lining.

Embryonic Stage

he second stage of development, from Week 3 to Week 8. This period involves the most rapid changes and is the most vulnerable time because the body's structures are actively developing.

Fetal Stage

The final stage of development, from Week 9 to Birth (~Week 38–40). It is characterized by "growth and finishing."

Zygote → Morula → Blastocyst

The progression of the organism during the Germinal stage. It begins as a single-cell zygote (Day 1), becomes a 4-cell organism (Day 2/3), a morula (Day 4/5), and finally a blastocyst (Day 5/6).

Ectoderm

The outer layer of the embryo that develops into the nervous system, skin, and inner ear.

Mesoderm

The middle layer of the embryo that develops into the muscles, bones, and circulatory system.

Endoderm

The inner layer of the embryo that develops into the digestive system, lungs, and glands.

Age of Viability

The point at which a fetus can potentially survive outside the womb, typically between 22 and 26 weeks.

Quickening

The first fetal movements felt by the mother, usually occurring between weeks 17 and 20.

Ectopic Pregnancy

An "out of place" pregnancy where the blastocyst implants outside the uterus, typically in the fallopian tube. These are nonviable and can be life-threatening to the mother.

Monozygotic Twins

Identical twins who share the same genetic makeup (though influenced by epigenetics). They occur in roughly 4 out of 1,000 births in the U.S. and have no known genetic predisposition.

Teratogens

External agents (such as drugs, chemicals, or viruses) that can disrupt prenatal development. Their impact depends on dose-response, individual differences, cumulative effects, and sensitive periods.

Thalidomide

A sedative prescribed in the 1950s/60s for morning sickness. If taken between the 4th and 6th weeks, it caused major limb deformities and damage to ears, hearts, and kidneys

Infant Mortality

The death of an infant within the first year of life. The U.S. rate is 5.4 per 1,000 live births, which is higher than the OECD average of 4.1

Maternal Mortality

Death related to or aggravated by pregnancy occurring during pregnancy, childbirth, or within 42 days afterward. The U.S. rate (23.8 per 100,000) is significantly higher than the OECD average (9.8).

Tylenol (Acetaminophen) Facts

There is no scientific evidence that taking acetaminophen during pregnancy causes autism.

Weeks 9–12

Forms fist, sucks thumb, sex detectable (by wk 12), fingernails, and tooth buds form.

Weeks 13–25

Responsive to sensory stimulation; heart/brain not yet capable of supporting life.

Weeks 26–40

Growth of cerebral cortex; sensitive to pain (at 27 wks); movement decreases.