- Describe the stages of prenatal development and the significance of prenatal care
- Describe infant reflexes
- Explain the physical development that occurs from infancy through childhood
- Explain key milestones in Piaget’s sensorimotor and preoperational stages
- Explain key milestones in Piaget’s concrete operational and formal operational stages
As discussed at the beginning of this module, developmental psychologists often divide our development into three areas: physical development, cognitive development, and psychosocial development. Mirroring Erikson’s stages, lifespan development is divided into different stages that are based on age. We will discuss prenatal, infant, child, adolescent, and adult development.
How did you come to be who you are? From beginning as a one-cell structure to your birth, your prenatal development occurred in an orderly and delicate sequence. There are three stages of prenatal development: germinal, embryonic, and fetal. Let’s take a look at what happens to the developing baby in each of these stages.
Germinal Stage (Weeks 1–2)
Parents’ DNA is passed on to a child at the moment of conception. Conception occurs when sperm fertilizes an egg and forms a zygote (Figure 1). A zygote begins as a one-cell structure that is created when a sperm and egg merge. The genetic makeup and sex of the baby are set at this point. During the first week after conception, the zygote divides and multiplies, going from a one-cell structure to two cells, then four cells, then eight cells, and so on. This process of cell division is called mitosis. Mitosis is a fragile process, and fewer than one-half of all zygotes survive beyond the first two weeks (Hall, 2004). After 5 days of mitosis there are 100 cells, and after 9 months there are billions of cells. As the cells divide, they become more specialized, forming different organs and body parts. In the germinal stage, the mass of cells has yet to attach itself to the lining of the uterus. Once it does, the next stage begins.
Embryonic Stage (Weeks 3–8)
After the zygote divides for about 7–10 days and has 150 cells, it travels down the fallopian tubes and implants itself in the lining of the uterus. Upon implantation, this multi-cellular organism is called an embryo. Now blood vessels grow, forming the placenta. The placenta is a structure connected to the uterus that provides nourishment and oxygen from the mother to the developing embryo via the umbilical cord. Basic structures of the embryo start to develop into areas that will become the head, chest, and abdomen. During the embryonic stage, the heart begins to beat and organs form and begin to function. The neural tube forms along the back of the embryo, developing into the spinal cord and brain.
Fetal Stage (Weeks 9–40)
When the organism is about nine weeks old, the embryo is called a fetus. At this stage, the fetus is about the size of a kidney bean and the “tail” begins to disappear. From 9–12 weeks, the sex organs begin to differentiate. At about 16 weeks, the fetus is approximately 4.5 inches long. Fingers and toes are fully developed, and fingerprints are visible. By the time the fetus reaches the sixth month of development (24 weeks), it weighs up to 1.4 pounds. Hearing has developed, so the fetus can respond to sounds. The internal organs, such as the lungs, heart, stomach, and intestines, have formed enough that a fetus born prematurely at this point has a chance to survive outside of the womb. Throughout the fetal stage the brain continues to grow and develop, nearly doubling in size from weeks 16 to 28.
Around 36 weeks, the fetus is almost ready for birth. It weighs about 6 pounds and is about 18.5 inches long, and by week 37 all of the fetus’s organ systems are developed enough that it could survive outside the uterus without many of the risks associated with premature birth. The fetus continues to gain weight and grow in length until approximately 40 weeks. By then, the fetus has very little room to move around and birth becomes imminent. The progression through the stages is shown in Figure 2.
Prenatal Influences
During each prenatal stage, genetic and environmental factors can affect development. The developing fetus is completely dependent on the gestational parent for life.
Prenatal care, which encompasses medical care during pregnancy for both the gestational parent and the fetus, holds significant importance for multiple reasons. It plays a crucial role in promoting optimal development, monitoring overall health, early detection of potential risks, and providing essential education and guidance.
According to the National Institutes of Health ([NIH], 2013), routine prenatal care is important because it can reduce the risk of complications during pregnancy. In fact, people who are trying to or may become pregnant should discuss pregnancy planning with a trusted healthcare professional. They may be advised, for example, to take a vitamin containing folic acid, which helps prevent certain birth defects, or to monitor aspects of their diet or exercise routines.
Recall that when the zygote attaches to the wall of the gestational parent’s uterus, the placenta is formed. The placenta provides nourishment and oxygen to the fetus. Most everything the parent ingests, including food, liquid, and even medication, travels through the placenta to the fetus, hence the common phrase “eating for two.” Anything the gestational parent is exposed to in the environment affects the fetus; if they are exposed to something harmful, the child can show life-long effects.
A teratogen is any environmental agent—biological, chemical, or physical—that causes damage to the developing embryo or fetus. There are different types of teratogens.
Fetal alcohol spectrum disorders (FASD) are a collection of birth defects associated with heavy consumption of alcohol during pregnancy. Physically, children with FASD may have a small head size and abnormal facial features. Cognitively, these children may have poor judgment, poor impulse control, higher rates of ADHD, learning issues, and lower IQ scores. These developmental problems and delays persist into adulthood (Streissguth et al., 2004). Based on studies conducted on animals, it also has been suggested that a gestational alcohol consumption during pregnancy may predispose a child to like alcohol (Youngentob et al., 2007).
| Facial Feature | Potential Effect of Fetal Alcohol Syndrome |
|---|---|
| Head size | Below-average head circumference |
| Eyes | Smaller than average eye opening, skin folds at corners of eyes |
| Nose | Low nasal bridge, short nose |
| Midface | Smaller than average midface size |
| Lip and philtrum | Thin upper lip, indistinct philtrum |
Smoking is also considered a teratogen because nicotine travels through the placenta to the fetus. When the gestational parent smokes, the developing baby experiences a reduction in blood oxygen levels. According to the Centers for Disease Control and Prevention (2013), smoking while pregnant can result in premature birth, low-birth-weight infants, stillbirth, and sudden infant death syndrome (SIDS).
Certain substances, such as heroin, cocaine, methamphetamine, almost all prescription medicines, and most over-the-counter medications are also considered teratogens. Babies who have been exposed to these substances may experience withdrawal symptoms or exhibit physiological responses that reflect their prenatal experiences. It’s important to provide appropriate medical care and support to ensure their safety and well-being. Other teratogens include radiation, viruses such as HIV and herpes, and rubella (though most people in the U.S. receive childhood vaccinations against rubella).
Each organ of the fetus develops during a specific period in the pregnancy, called the critical or sensitive period (Figure 2). For example, research with primate models of FASD has demonstrated that the time during which a developing fetus is exposed to alcohol can dramatically affect the appearance of facial characteristics associated with fetal alcohol syndrome. Specifically, this research suggests that alcohol exposure that is limited to day 19 or 20 of gestation can lead to significant facial abnormalities in the offspring (Ashley, Magnuson, Omnell, & Clarren, 1999). Given regions of the brain also show sensitive periods during which they are most susceptible to the teratogenic effects of alcohol (Tran & Kelly, 2003).
Chasnoff’s research focused on a specific group of individuals living in poverty who used cocaine, primarily consisting of low-income urban populations with multiple risk factors. Methodological limitations make it problematic to generalize the findings to the broader population of pregnant individuals using cocaine. Unfortunately, the media’s portrayal of crack babies perpetuated anti-Black stereotypes, disproportionately affecting communities of color and reinforcing misconceptions that linked drug use to moral character. This focus on crack cocaine overshadowed other social factors contributing to substance abuse and obscured the broader context of maternal health. The crack baby myth perpetuated harmful stereotypes and overlooked systemic issues surrounding drug addiction and maternal well-being.
Is it okay to charge expectant parents for drug use?
Addressing substance use during pregnancy requires thoughtful consideration of effective and ethical approaches to support pregnant individuals and promote the well-being of both mothers and children. One case that invites critical examination is the Interagency Policy on Management of Substance Abuse During Pregnancy implemented in Charleston, South Carolina. This policy aimed to deter drug use through mandatory screenings and legal actions, but it faced significant challenges and negative outcomes, prompting us to reflect on its limitations and explore alternative strategies
This policy seemed to deter pregnant people from seeking prenatal care, deterred them from seeking other social services, and was applied solely to low-income women, resulting in lawsuits. The program was canceled after 5 years, during which 42 women were arrested. A federal agency later determined that the program involved human experimentation without the approval and oversight of an institutional review board (IRB).
- What were the flaws in the program and how would you correct them?
- What are the ethical implications of charging pregnant women with child abuse?