Prenatal Development Chapter 4

Chapter Objectives List the methods of family planning. Outline what occurs during each of the three stages of prenatal development Contrast miscarriage and stillbirth. Identify how ten major birth defects can be diagnosed. Summarize the hazards that alcohol and other drugs pose to prenatal development. Assess why environmental hazards must be avoided during pregnancy. Describe how a fetus can be affected by certain illnesses the mother may contract.

Section 4.1 The Developing Baby

Main Idea A man’s sperm fertilizes a woman’s egg to begin developing an infant. Many contraception methods are available.

Vocabulary Content Vocabulary Academic Vocabulary Ovum Infertility Uterus Surrogate Fallopian tube Prenatal development Sperm Zygote Conception Embryo Chromosome Amniotic fluid Gene Placenta Genome Umbilical cord DNA Fetus Controversial Spontaneous

Conception Woman have a 28 day cycle in which an ovum is released during ovulation. Ovum – egg cell Uterus – organ in a woman’s body in which a baby develops during pregnancy. The ovary releases the ovum into fallopian tube – tube that connects the ovary to the uterus. The journey takes about two days. The ovum is fertilized by the sperm –(male reproductive cell) in the fallopian tube.

Conception Conception – process of the sperm fertilizing the egg. If the ovum is not fertilized then the uterus sheds it’s lining.

Role of Genetics Chromosome – tiny threadlike structure in the nucleus of every cell. Gene – unit that determines human’s inherited characteristics. Genome – complete blueprint for the creation of a person. DNA (deoxyribonucleic acid) – complex molecules that make up genes.

Multiple Births Two types of twins Identical – one egg and one sperm Fraternal – two eggs and two sperm

Infertility Infertility – inability to conceive a child. 40% are because of female infertility, 40% are because of male infertility, and 20% are either unexplained or because of both male and female infertility. Surrogate – a substitute

Three Stages of Pregnancy Prenatal Development – baby’s development during pregnancy The Germinal Stage The Embryonic State The Fetal Stage

Germinal Stage Zygote – fertilized egg. This stage lasts about two weeks Cell division Implantation

The Embryonic Stage Embryo – is what the developing baby is called from about the third week of pregnancy through the eight week. Organs and body systems Amniotic sac – sac filled with liquid forms around the embryo Placenta and umbilical cord Placenta – tissue that connects the developing baby to the uterus Umbilical cord – long tube that connects the baby to the placenta

The Fetal Stage Fetus – around eight or ninth week of pregnancy to birth. Making movements Completing development Staying active Growing bigger Ready for birth

Section 4.2 Problems in Prenatal Development

Main Idea Not all pregnancies end in the birth of a healthy infant. Some end early with the unborn baby’s death. Some babies are born with health problems.

Vocabulary Content Vocabulary Academic Vocabulary Miscarriage Stillbirth Ultrasound Amniocentesis Predisposition Serious

Losing a Baby Miscarriage – when the developing baby dies before the 20th week. Stillbirth – when the baby dies after the 20th week. About 15 to 20 percent of pregnancies end in miscarriage.

Types and Causes of Birth Defects Factors in the environment Hereditary factors Errors in chromosomes A combination of environmental and hereditary factors

Factors in the Environment The nutritional balance of the mother’s diet Any diseases or infections the mother has during pregnancy Harmful substances the mother consumes Some medicines that benefit the mother but harms the baby Air pollution Exposure to x-rays, high levels of radiation, and certain chemicals

Hereditary Causes Every person has between 20,000 and 25,000 genes that determine their traits. It is normal to get 5 or 6 imperfect genes passed on. When we receive an imperfect gene from both parents then it is called a recessive inheritance and could cause a defect. When we receive an imperfect gene from one parent and causes a defect then it is called a dominant inheritance.

Errors in Chromosomes Birth defects are caused by problems in the number or structure of chromosomes. May occur when an egg or sperm cell is developing.

Interaction of Heredity and Environment Some birth defects are caused by a combination of heredity and environment. Such as cleft lip or palate, and spina bifida.

Prevention and Diagnosis of Birth Defects Genetic Counseling May have birth defects in the family Assess their risk of having a baby with birth defects Prenatal Test Alpha-fetoprotein (AFP) – blood test that tests for a protein that is released by the unborn baby’s liver that is released into the mother’s blood stream Ultrasound – test that uses soundwaves to make a video image of an unborn baby Amniocentesis – drawing a sample of amniotic fluid surrounding the unborn baby Chorionic Villi Sampling – sample of tissue from the membrane that encases the fetus to test for specific birth defects

Section 4.3 Avoiding Dangers to the Baby

Main Idea A fetus needs to be protected from many dangers. These include the mother drinking alcohol or taking other drugs, environmental hazards, diseases, and infections.

Vocabulary Content Vocabulary Academic Vocabulary Fetal Alcohol Syndrome (FAS) Fetal Alcohol Effects SIDS Toxoplasmosis Deformity Congenital

Effects of Alcohol and Other Drugs on Pregnancy Alcohol, in any form Prescription and over-the-counter medicines Caffeine Nicotine and other toxic chemicals found in cigarettes Illegal drugs such as heroin, LSD, ecstasy, marijuana, and cocaine Inhalants

Alcohol Fetal alcohol syndrome (FAS) – incurable condition found in some children of mothers who consumed alcohol during pregnancy. Hyperactivity, kidney defects, facial deformity, as well as possible mental retardation, and problems with learning, attention, memory, and problem solving. Fetal alcohol effects – are abnormalities caused by the mother consuming alcohol during pregnancy

Prescription Drugs and Over-the-Counter Drugs Check with the doctor before taking any medication Many drugs can harm the development of the unborn baby Can cause slow growth, infections, or bleeding at birth

Caffeine Can increase fetal heart rate and movement Can draw fluid and calcium out of the body Cause increased risk of miscarriage, premature birth, and low birth weight

Tobacco Can cause low birth weight, premature birth, respiratory infections and allergies

Illegal drugs Babies may be born with an addiction if their mothers are addicted to drugs during pregnancy and will go through withdrawal once they are born. Risk of miscarriage, stroke, heart attack, low birth weight, feeding difficulties, developmental delays SIDS – Sudden infant death syndrome, unexpected death of a baby under one year of age with no clear cause.

Environmental hazards X-rays Hazardous substances Paint Pesticides Lead Carbon monoxide Mercury Solvents, paint thinners, formaldehyde

Diseases and Infections Rubella Toxoplasmosis – infection caused by a parasite Chicken pox Sexually transmitted infections