Assignment on Prenatal Development
Assignment on Prenatal Development
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Assignment on Prenatal Development
There are three stages of prenatal development that occur in the 38 weeks of pregnancy: the zygote, the embryo and the fetus.
Zygote
When the sperm fertilizes the ovum, the fertilized egg or zygote implants in the uterine wall. The zygote stage is about two weeks.
Week 1
Week 2
Embryo
Once the zygote is implanted, the embryo stage begins. The physiological structures and systems begin to develop, the embryo begins to look like a human, and in the eight weeks since fertilization its size increases by around two million percent. Development occurs from the head down (cephalocaudal), and from the center out (proximal-distal). By the end of the embryonic stage, the fingers and toes are visible. Most miscarriages occur in this period because the embryo detaches from uterine wall.
Week 3
Week 4
Week 5
Week 6
Week 7
Week 8
Fetus
The final stage, the fetus, begins in the third month of pregnancy. Muscles and the central nervous system cause movement and reflexes like swallowing. If babies are born prematurely, between 22 and 26 weeks, their systems may be developed enough to survive. This is called the period of viability. If they are too premature they may not survive because their respiratory systems are not sufficiently developed.
Week 9
Week 16
Week 20
Week 38
Risks
Teratogens are external agents that cause fetal development problems by disturbing the motor, neural, emotional, cognitive and physical systems. Teratogens include:
· Illegal, prescription and nonprescription drugs, alcohol and nicotine.
· Environmental toxins such as pesticides, herbicides, household cleaners, radiation, lead, cosmetics and food additives.
· Medical interventions in pregnancy and childbirth.
· Maternal diseases and disorders such as mumps, rubella and Rh factor incompatibility where the mother’s and infant’s blood are incompatible.
· Bacterial, viral and parasitic infections such as toxoplasmosis, gonorrhea, chlamydia, syphilis and HIV/AIDS.
· Maternal age. Women under the age of 15 and over the age of 35 have more complications.
· Poor diet.
· Stress and negative emotions.
Birth
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· Birth
Parents experience many emotions around the time of birth such as anticipation, anxiety, excitement, fear, joy and awe. Birth is also an intense and complex experience for the infant as it leaves its familiar warm, dark and wet environment in the uterus, and faces the next stage of its life in a dry, bright environment.
Birth involves three stages. In the first stage, the mother goes into labor and experiences contractions. In the second stage, the infant is born by passing through the birth canal and vaginal opening. In the last stage, the uterus expels the placenta.
Natural childbirth has become more popular since the 1970s (Parke & Gauvain, 2009). More mothers are sharing the experience with their families at home or birthing centers, using midwives and preparing for birth with their partners. Lamaze is a popular method that involves the mother-to-be and her partner. The method teaches the couple how the mother-to-be should breath and relax her muscles to make childbirth easier. Water births, birthing stools and giving birth in the kneeling position are also becoming more popular.
If there are birthing complications, women may need to be hospitalized. Cesarean sections surgically remove the infant through an incision in the mother’s abdomen. Cesarean sections assist mothers and infants who are having difficulty in the birth process, and are convenient for physicians and families who wish to plan their schedules.
There are disadvantages associated with Cesarean sections, including longer recovery times and increased risk of infection for mothers, lower birthweights in subsequent births, increased infant exposure to maternal medications and more trouble breathing and breastfeeding (Emory, Schlackman & Fiano, 1996; Kennare, 2007; Liu, 2007).
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