1. C HAPTER 19 Pregnancy, Birth, and Childhood

2. L IFE C YCLE During sexual intercourse, sperm from the man are deposited into the vagina The sperm swim through the uterus to the fallopian tubes If the egg is on its way to the uterus, a sperm may fertilize it This moment of fertilization is called conception

3. F ERTILIZATION In the first weeks after fertilization, the fertilized egg undergoes many cell divisions and travels to the uterus The united egg and sperm is called a zygote The original cell divides to make two cells Embryo: the two-cell stage until about nine weeks after fertilization in the growing structure Blastocyst: after 5 days after fertilization, the embryo reaches the uterus, where it floats free for a few days. It is now made of 50-100 cells. The structure is no longer a solid mass of cells, but a sphere of cells surrounding a hollow center

4. I MPLANTATION The blastocyst forms and then attaches itself to the wall of the uterus called implantation Amniotic Sac: a fluid filled bag of thin tissue develops around the embryo after implantation. The sac continues to grow in size as the embryo grows Placenta: The attachment holding the embryo to the wall of the uterus develops Oxygen and nutrients move from the mother’s blood into tiny blood vessels that lead to the embryo

5. D EVELOPMENT Umbilical cord: 25 days after fertilization, a ropelike structure develops between the embryo and placenta The growing embryo: during the first 2 months major organs start to form (a heart, kidneys, endocrine glands) By the end of 8 weeks, the embryo is an inch long The head makes up about 50 percent of the length of the embryo

6. F ETUS From month 3 until birth the developing human is called a fetus Month 3-6, the fetus begins to move and kick, a sign that its skeleton and muscles are developing Months 7-9, continues to grow and develop Body fat accumulates, eyelids open and close End of 9 months, the fetus is ready to be born

7. P REGNANCY Proper Nutrition: Extremely Important A woman needs to consume about 300 calories more a day Folic acid: essential for proper development of an embryo’s neural tube which later develops into the spinal cord and brain Exercise: A fit woman will better meet the extra energy demands of carrying the fetus Avoiding alcohol and other drugs: abstain from all alcohol, tobacco, and any other drugs not presribed

8. A VOIDING E NVIRONMENTAL H AZARDS X-rays: radiation from x-rays can harm a developing embryo or fetus Lead: main source of exposure to lead is from lead based paint present in older homes Mercury: exposure to this comes from eating contaminated fish Cat litter: cat feces can contain a parasite that is especially dangerous to a developing fetus

9. P RENATAL C ARE Prenatal care: medical care during pregnancy Obstetrician: doctor specializing in pregnancy and childbirth Trimesters: pregnancy is divided into three periods of time (around 3 months long)

10. F IRST T RIMESTER Record medical history and weight Note conditions that could affect the pregnancy Prescribe prenatal vitamins as needed

11. S ECOND T RIMESTER Monitor heartbeat of fetus Measure growth of uterus Monitor for complications using ultrasound and other tools

12. T HIRD T RIMESTER Check position and size of fetus Check for warning signs of premature, or early birth Continue to monitor for complications Discuss birth process

13. M ONITORING Ultrasound: High frequency waves are used in most pregnancies to create an image of the developing fetus Gender of the baby More than one fetus Chronic villus sampling: around the 8 th week a test that the doctor removes ad tests a small piece of the developing placenta

14. C ONTINUED 14 th -16 th of pregnacy: Amniocentesis: procedure involves inserting a needle into a woman’s abdomen and uterus to remove a small amount of amniotic fluid surrounding the fetus

15. C OMPLICATIONS Eptopic Pregnancy: the blastocyst implants in the fallopian tube instead of the uterus Miscarriage: the death of an embryo in the first 20 weeks of pregnancy Preclampsia: toxemia, characterized by high blood pressure and high levels in the urine, fetus is not getting enough oxygen, bed rest Gestational Diabetes: diabetes in pregnant women, high blood sugar levels

16. C HILDBIRTH 3 phases: labor, delivery, and delivery of afterbirth Labor: Pushing the fetus out Last from 2-24 hours Contractions of the muscles of the uterus cause the cervix to increase in width or dilate Each contraction lasts from 30 to 90 seconds

17. D ELIVERY OF B ABY This stage can last from 30 minutes to 2 hours Contractions continue of the uterus and the baby is pushed out usually head first through the cervix and then vagina The doctor will clamp and cut the umbilical cord The baby’s mouth and nose are suctioned to get out the mucus Eye drops are used to prevent infection

18. D ELIVERY OF A FTERBIRTH The third stage involves contrations of the uterus that push out the placenta, afterbirth This stage typically takes 15-30 minutes Postpartum Period: during the first six weeks many changes take place Mother is changing hormone levels signal the breast to produce milk and the uterus to shrink

19. C OMPLICATIONS AT B IRTH Some complications result in a surgical delivery or premature birth. Low birth weight and the birth of more thank one baby also may cause complications A still birth occurs when a fetus dies and is expelled from the body after the 20 th week of pregnancy Cesarean section: surgical method of birth Operation takes about one hour

20. P REMATURE B IRTH Delivery of a baby before the 37 th week of pregnancy is called premature birth The earlier the birth the more complications Incubator: a chamber designed to protect the baby until it has developed. Low birthweight: A newborn that weighs less than 5.5 pounds

21. M ULTIPLE BIRTHS Identical Twins: develop from a single fertilized egg or zygote, embryo divides into two identical twins Fraternal Twins: two eggs are released from the ovary and are fertilized by 2 sperm Triplets or more: has increased dramatically in the last 25 years

22. C HILDHOOD Birth-18 months: Learn to smile about one month Cries to help Learns to sit, crawl, stand, and walk Cries Recognizes parents Baby teeth and can chew food

23. C HILDHOOD 18 months-3 years Learn to talk play alongside others Learns many words Baby fat is lost and the arms and legs get longer Appetite decreases as growth slows down

24. T HREE TO S IX Y EARS Most lose all traces of babyhood Muscle grow, energy is high, and the curious child is “into everything” Plays with others Has lots of energy

25. S IX TO T WELVE Y EARS Becomes less self-centered Has many interests and hobbies Middle and Late Childhood Physical growth, mastering new skills, and making friends are key areas of development during middle and late childhood Pre-adolescence or the tween years: late childhood before adolescence