The Prenatal Period The Prenatal Environment: Threats to Development

Fertilization Moment of conception –Joining of sperm and ovum = zygote ANATOMY OF THE FEMALE REPRODUCTIVE ORGANS The basic anatomy of the female reproductive organs is illustrated in this cutaway view. Source: Moore & Persaud, 2003.

Stages of Prenatal Development GerminalEmbryonicFetal

Germinal Stage Fertilization  two weeks –Shortest stage –Fertilized egg now called blastocyst –Blastocyst travels to and implants in uterus –Characterized by methodical cell division –With division comes cell specialization

Embryonic Stage 2 weeks  8 weeks –Organism firmly secures to uterus and is called an embryo –Development of major organs and basic anatomy Three distinct layers that ultimately form different sets of structures: –Ectoderm –Endoderm –Mesoderm Embyro at 5-6 weeks

Body Proportions During the fetal period, the proportions of the body change dramatically. At 2 months, the head represents about half the fetus, but by the time of birth, it is one- quarter of its total size.

Fetal Stage 8 weeks  Birth –Formally starts when differentiation of major organs has occurred –Organism now called fetus –Characterized by rapid development Organs become more differentiated and begin working Interconnections between body parts become more complex and integrated Brain becomes more sophisticated Fetus at 8 weeks Fetus at 14 weeks

Pregnancy Problems

Infertility Parental age Use of illicit drugs, cigarettes, bouts of STIs Treatments Artificial insemination (ICI, IUI, IVF, GIFT, ZIFT)

OLDER WOMEN AND RISKS OF PREGNANCY Not only does the rate of infertility increase as women get older, but the risk of chromosomal abnormality increases as well. Source: Reproductive Medicine Associates of New Jersey, 2002.

Fertilization joins the sperm and ovum to start prenatal development. The prenatal period consists of three stages: germinal, embryonic, and fetal.

In addition to difficulties in conceiving due to infertility, some 15 to 20 percent of all pregnancies end in miscarriage, usually in the first several months of pregnancy.

The fertility treatment in which fertilization is induced inside the mother's body is known as_________. a. artificial insemination b. intracervical insemination c. intrauterine insemination d. in vitro fertilization

Fertilization that occurs outside the mother's body is called ____________. a. artificial insemination b. infertility c. in vitro fertilization (IVF) d. intracervical insemination

In your opinion, is it wiser for a woman to ask a friend or a stranger to be the surrogate mother for her child? Why?

The Prenatal Environment: Threats to Development Teratogen Includes environmental agent such as a drug, chemical, virus, or other factor that produces a birth defect Related to time and quantity of exposure (See Figure 2-12 or the next slide for a teratogen sensitivity timeline)

Teratogen Sensitivity Timeline

Mother's Prenatal Influence DietAgeHealthDrug UseAlcohol UseTobacco Use

Father's Prenatal Influence Tobacco useDrug useAlcohol useTreatment of mother

Optimizing the Prenatal Environment Avoid X-rays and birth control pills; get rubella vaccination Eat well and take prenatal vitamins Avoid alcohol use and other drugs Monitor caffeine intake. Avoid smoking and exposure to secondhand smoke Exercise regularly

The prenatal environment significantly influences the development of the baby. The diet, age, prenatal support, and illnesses of mothers can affect their babies' health and growth. Mothers' use of drugs, alcohol, tobacco, and caffeine can adversely affect the health and development of the unborn child. The behavior of fathers and others also affect the child.

Eating well and nutritiously, exercising regularly, avoiding alcohol and tobacco, and controlling caffeine intake are sound strategies for averting threats to the fetal environment.

Match the following descriptions of prenatal development to their appropriate labels: germinal, embryonic, and fetal. a. This stage lasts from 8 weeks until birth and involves the differentiation of major organs. ______________ b. From 2 to 8 weeks following fertilization, when the major organs and basic anatomy begin developing. ______________ c. The first and shortest stage, where the zygote begins to divide and grow in complexity during the first 2 weeks following conception. ______________

A ______________ is an environmental agent such as a drug, chemical, virus, or other factor that produces a birth defect. a. terminal button b. teratogen c. terrapin d. chromosome

Studies show that “crack babies” who are now entering school have significant difficulty dealing with multiple stimuli and forming close attachments. How might both genetic and environmental influences combined to produce these results?