ECE133: Growth & Development of Children

Topic 2: Fetal Development

Foetal Development

• Foetal development (or prenatal development) is the period between conception and birth.
• This period is generally divided into THREE Stages: The germinal stage, the embryonic stage and the foetal stage.

Stage 1: The Germinal Stage

• The two-week period after conception is called the germinal stage. Conception occurs when a sperm cell combines with an egg cell to form a zygote. About thirty-six hours after conception, the zygote begins to divide quickly (see Figure 2.1).
• The resulting ball of cells moves along the mother’s fallopian tube to the uterus
• Zygote divided This process is called implantation and takes about a week to complete.
• If implantation fails, as is quite common, the pregnancy terminates.
• One key feature of the germinal stage is the formation of a tissue called the placenta.
• The placenta has two important functions:
• Passing oxygen and nutrients from the mother’s blood into the embryo or foetus
• Removing waste materials from the embryo or foetus

Stage 2: The Embryonic Stage

• The embryonic stage lasts from the end of the germinal stage to two months after conception.
• The developing ball of cells is now called an embryo. In this stage, all the major organs form, and the embryo becomes very fragile.
• The biggest dangers are teratogens, which are agents such as viruses, drugs, or radiation that can cause deformities in an embryo or foetus.
• At the end of the embryonic period, the embryo is only about an inch long.
• During the embryonic period, cells begin to take on different functions.
• The brain, heart, lungs, internal organs and arms and legs begin to form. Once baby is a foetus, growth and development are aimed at prepping baby for life on the outside.

Stage 3: The Foetal Stage

• The last stage of prenatal development is the foetal stage, which lasts from two months after conception until birth.
• About one month into this stage, the sex organs of the foetus begin to form.
• The foetus quickly grows as bones and muscles form, and it begins to move inside the uterus.
• Organ systems develop further and start to function.
• During the last three months, the brain increases rapidly in size, an insulating layer of fat forms under the skin, and the respiratory and digestive systems start to work independently.

Foetal Viability

• Around twenty-two to twenty-six weeks after conception, the foetus reaches the age of viability, after which it has some chance of surviving out-side the womb if it is born prematurely.
• The chances of a premature baby’s survival increase significantly with each additional week it remains in the mother’s uterus.

Foetal Development : Month by Month

Foetal Development : Month by Month

Foetal Development : Month by Month

Foetal Development : Month by Month

Foetal Development : Month by Month

Foetal Development : Month by Month

Foetal Development : Month by Month

Adverse Factor Affecting Foetal Development

Although the womb provides protection, the foetus remains indirectly connected to the outside world through its mother.

Several factors that are linked to the mother can harm the foetus:

• Poor nutrition

• Use of alcohol

• Smoking

• Use of certain prescription or over-the-counter drugs

• Use of recreational drugs such as cocaine, sedatives, and narcotics

• X-rays and other kinds of radiation

• Ingested toxins, such as lead

• Illnesses such as AIDS, German measles, syphilis, cholera, smallpox, mumps, or severe flu

• Foetal Alcohol Syndrome

Smoking

• Smoking is not only bad for you, but bad for your baby as well.
• Smoking during pregnancy reduces the amount of oxygen that the baby receives and increases the risk of miscarriage, bleeding, and morning sickness.
• Chemicals inhaled while smoking may lead to other health problems with the baby.
• Reduced birth weight, premature birth, increased risk of SIDS, and stillbirth are other possible consequences. Pregnant women should also avoid second hand smoke.

• Alcohol – Drinking can cause foetal alcohol syndrome, including symptoms like low birth weight, medical problems, and behaviour abnormalities. As soon as you know you are pregnant, stop drinking.

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• Caffeine – There are many conflicting studies about caffeine and pregnancy and some believe that caffeine is not as harmful as it was once thought to be. Nevertheless, the FDA warns against caffeine consumption during pregnancy and suggests quitting or reducing consumption at the very least. Caffeine has been shown to affect foetal heart rates and awake time (foetuses grow when sleeping). Decaffeinated coffee can also be harmful since producers often add additional chemicals to remove the caffeine. Caffeine can also increase risk of stretch marks. Suddenly quitting coffee intake can cause headaches; so most experts recommend gradually reducing the amount consumed.

Nutrition – Good nutrition is crucial to a developing child, particularly getting enough folic acid. Lack of folic acid can cause birth defects. At least 400-1000 micrograms of this B vitamin is suggested (about ten times more if you’ve already had a child with neural tube birth defects) starting one month before pregnant and throughout the entire pregnancy. Leafy vegetables, orange juice, and beans are some natural sources of folic acid. Many stores sell vitamins with folic acid.

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Exercise – Moderate exercise is helpful as it improves the mother’s mental state and can increase oxygen flow to the foetus. However, over-exertion can be dangerous. Most experts recommend reducing exercise your intensity during pregnancy. Activities like walking, swimming, and yoga are popular for pregnant women.

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Prenatal Care – Regular doctor visits are important to your baby’s development. The body undergoes many changes during pregnancy. Some side effects may be completely normal, whereas other may not. Regular monitoring by a professional will help ensure that your baby will be born healthy.

Multiple sex partners – Multiple sex partners can increase risk of STD’s, which in turn may lead to birth and pregnancy complications, like low birth weight or premature birth.

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Exposure to chemicals – During pregnancy, reduce exposure to unnatural chemicals, particularly pesticides in food. Many people now eat organic produce, which is grown without chemicals. The simplest precaution to take before consuming vegetables or fruits is to wash them thoroughly. Also, removing the outer surface of vegetables can be helpful since most pesticides will rest on the outside of the vegetable or fruit.

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Other factors – Many other factors can affect foetal development, including heart disease, the mother’s age (before 15 years and after 35 years is riskier), asthma, excessive stress or depression, diseases, and bleeding.