The pregnancy goal is to have a healthy, full-term infant weighing 7 to 9 pounds and a healthy mother. To help ensure that all goes well during the life cycle of a baby in the womb, the mother needs to prepare by attaining a healthy weight, quitting any harmful habits such as smoking, drugs or alcohol and control any chronic disease such as diabetes or high blood pressure, according to Kathleen Mahan and Sylvia Escott-Stump in "Krause's Food, Nutrition, & Diet Therapy."
Identification
The life cycle of a baby in the womb includes the germinal, embryonic and fetal periods. During the germinal period, the first two weeks of pregnancy, differentiation of cells occurs. In the embryonic period, weeks two to eight after conception, rapid cell differentiation and development of specific tissues, organs and systems occurs. The last seven months of pregnancy involve rapid growth with elaboration of tissues and organs and functional activities of developing body systems.
Features
The course of a pregnancy is typically described as being divided into three-month segments. The first trimester is a period of rapid growth that begins with a fertilized egg and ends three months later with a baby measuring only 2 1/2 to 3 inches long from the crown of the head to the rump and weighing only about 1/2 to 1 ounce. But it has a heartbeat, arms and legs. The baby's brain, spinal cord and other organs form and fingers and toes take shape.
The sex of the baby is evident during the second trimester and she can smile or frown. She begins to kick, make facial expressions and can hear. By week 27, the lungs, liver and immune system are maturing and she has tripled in length since the first trimester.
During the third trimester the baby will experience rapid growth and gain significantly more weight in preparation for life outside of the womb. She opens her eyes and becomes very active. By the end of week 37 she is full term and ready for birth.
Function
Life stages are convenient markers for the purposes of discussion and planning, but life actually develops along a continuum. Life stages help doctors assess whether growth and development is on schedule and help parents envision and relate to the wonder of creation taking place.
Significance
Development may vary slightly from the schedule depicted in the life stages, but the chronology of events is the same for every pregnancy. The mother's age, nutrition, drug use and any environmental hazards need to be considered in relation to the stage of pregnancy and potential for the effect on the fetus or offspring.
A miscarriage happens when a pregnancy ends spontaneously before the developing fetus is mature enough to survive outside the womb. Researchers estimate 10 to 15 percent of pregnancies end this way. Induced abortion is a complex issue with ethical, medical, psychological and social aspects. A pregnancy that ends prematurely is stressful for all concerned regardless of how, when or in what stage it happens.
Considerations
The outside environment can affect the developing baby in many well-documented ways. Thousands of babies born with birth defects every year were affected by events that occurred in the mother's life during the pregnancy or as early as one to two months before conception. Maternal infections, diseases and conditions as well as teratogens, or things that can cause birth defects, can cause damage to an unborn child in fairly predictable ways, depending on the stage of development.
References
- "Krause's Food, Nutrition, & Diet Therapy, 10th Edition"; Mahan and Escott-Stump; 2000
- Mayo Clinic: Fetal Development: The First Trimester
- Mayo Clinic: Fetal Development: The Second Trimester
- Mayo Clinic: Fetal Development: The Third Trimester
