1. Life Span Development Prenatal Development and Birth – Chapter 4 June 15, 2004 Class #3

2. The First Trimester  Pregnancy is the process referring to the gestation period of a human being  A pregnancy is initiated when a fertile sperm from a male bonds with a fertile egg from a female  The period of pregnancy (from the woman's last menstrual cycle to the birth of the child) usually is 40 weeks  This 40 weeks is divided into three subperiods, known as "trimesters“  The first thirteen weeks of pregnancy are referred to as the "first trimester"

3. Development of the Embryo and Fetus  Obstetricians count "weeks of pregnancy" from the first day of a woman's last menstrual cycle because there is often no way to determine exactly when conception occurred  Embryologists, however, typically describe the developing embryo or fetus by the number of weeks since conception

4. From Zygote to Newborn  Germinal period—first 14 days  Embryonic period—3rd through 8th weeks  Fetal period—9th week through birth

5. Germinal: The First 14 Days Zygote divides and keep dividing (at least though 3rd doubling they are the same)Zygote divides and keep dividing (at least though 3rd doubling they are the same) At this stage (8 cells) differentiation beginsAt this stage (8 cells) differentiation begins -early “stem” cells take on distinct characteristics -they gravitate to locations, foreshadowing the type of cells they will become

6. Germinal: The First 14 Days At about a week after conception the multiplying cells separate into two massesAt about a week after conception the multiplying cells separate into two masses - first task of out cells to achieve implantation— embed themselves into the nuturant environment of the uterus 60% of all natural conceptions fail to implant; 70% of in vitro procedures fail to implant60% of all natural conceptions fail to implant; 70% of in vitro procedures fail to implant

7. Development of the Embryo and Fetus  The zygote’s outer part attaches to the uterine wall forming the placenta  The inner cells are referred to as the embryo  By nine weeks, the embryo clearly looks human and is now a fetus

8. Role of the Placenta  The placenta carries nourishment and oxygen from the mother to the fetus and at the same time screens out many potentially harmful substances –Unfortunately some get through…

9. Fetal Alcohol Syndrome (FAS)  FAS is a lifelong yet completely preventable set of physical, mental and neurobehavioral birth defects associated with alcohol consumption during pregnancy –Alcohol enters the mother’s and the fetus’ bloodstream  FAS is the leading known cause of mental retardation and birth defects –Small disproportioned head and lifelong brain abnormalities

10. How does a mother’s drinking affect her unborn child?  Facts: –Through the blood vessels in the placenta, the mother’s blood supplies the developing baby with nourishment and oxygen –If the mother drinks alcohol, the alcohol enters her blood stream and then, through the placenta, enters the blood supply of the growing baby  So, when a pregnant woman drinks alcohol, so does her baby –Alcohol is a teratogen, a substance known to be toxic to human development

11. Fetal Alcohol Syndrome (FAS)  Prenatal alcohol exposure does not always result in FAS—although there is no known safe level of alcohol consumption during pregnancy  Most individuals affected by alcohol exposure before birth do not have the characteristic facial abnormalities and growth retardation identified with FAS, yet they have brain and other impairments that are just as significant

12. Sad facts…  In addition to mental retardation, individuals with FAS may have other neurological deficits such as poor motor skills and hand-eye coordination  They may also have a complex pattern of behavioral and learning problems, including difficulties with memory, attention and judgment.  As many as 12,000 infants are born each year with FAS

13. What if I am pregnant and have been drinking?  If you consumed alcohol before you knew you were pregnant, stop drinking now! –Abstaining from alcohol for the remainder of your pregnancy can have a beneficial effect even on functions that might have been affected by earlier drinking –The sooner you stop drinking, the better the chance of having a healthy baby

14. Smoking cigarettes during pregnancy (US Dept. of Heath and Human Services, 2001)  The rate of smoking during pregnancy dropped 33 percent between 1990 and 1999, so that in 1999 just over 12 percent of all women reported smoking during their pregnancies, according to a new report from the Centers for Disease Control and Prevention –The greatest success in reducing smoking was for women in their late twenties and early thirties, where there was over a 40 percent drop since 1990 –Teenagers were more likely than women of any other age to smoke while pregnant  After experiencing a dramatic 20-percent decline in the first part of the decade, smoking rates among pregnant teenagers–unlike women of all other ages-- increased by 5 percent from 1994 to 1999  The highest rate in 1999 (19 percent) was for women 18-19 years of age

15. Smoking during pregnancy is related to violent crimes…  Brennan, Grekin, & Mednick (1999) –Subjects were a birth cohort of 4169 males born between September 1959 and December 1961 in Copenhagen, Denmark –During the third trimester of pregnancy, mothers self-reported the number of cigarettes smoked daily –When the male offspring were 34 years of age, their arrest histories were checked in the Danish National Criminal Register

16. Brennan, Grekin, & Mednick (1999)  Found the following data relating smoking during pregnancy to offsprings’ arrest rate for violent crimes: –Mother did not smoke…8% –Mother smoked 1-2 cigarettes per day…9% –Mother smoked 3-10 cigarettes per day…11% –Mother smoked 10-20 cigarettes per day…15% –Mother smoked > 20 cigarettes/day…18%  What do you think of these numbers???

17. Embryo: From the Third to the Eighth Week  First sign of human structure: thin line down the middle (22 days) that becomes the neural tube, which eventually forms the central nervous system, including brain and spinal column –fourth week  head begins to take shape  heart begins with a miniscule blood vessel that begins to pulsate

18. Embryo: From the Third to the Eighth Week –fifth week  arm and leg buds appear  tail-like appendage extends from the spine –eighth week  embryo weighs 1 gram and is 1 inch long  head more rounded; face formed  all basic organs and body parts (but for sex) present –20% of all embryos spontaneously abort now

19. Fetus  Called a fetus from 9th week on

20. Third Month Sex organs take shape (Y cell sends signal to male sex organs; for females, no signal occurs)Sex organs take shape (Y cell sends signal to male sex organs; for females, no signal occurs) -genital organs fully shaped by 12th week All body parts presentAll body parts present Fetus can move every part of bodyFetus can move every part of body Fetus weighs 3 ounces and is 3 inches longFetus weighs 3 ounces and is 3 inches long

21. First Trimester: For the Mom  There are a wide variety of changes that a woman can experience  These physical changes can also cause emotional reactions  Sometimes women during the first trimester notice an energy boost and overwhelming happiness; other women complain that they are fatigued and emotionally unstable; it is also possible for women to not even be aware of drastic fluctuations in their bodies and emotions  Many women worry that these changes during the first trimester may adversely affect the growth of the fetus, but in most cases they do not threaten the well-being of the fetus

22. First Trimester: For the Mom  Some pregnant women notice aches and pains  Common complaints are back pains, joint aches, and leg cramps  It is essential that the woman rests often in order to alleviate these aches  Almost all women notice that they are more tired than usual during the first trimester  This feeling of fatigue sometimes remains for the duration of the pregnancy, although most women feel noticeably stronger by the third trimester

23. “Morning Sickness”  Another problem that affects the mother during early pregnancy is nausea  This is a very common problem as it affects almost three- fourths of all pregnant women  Most doctors think that "morning sickness" is caused by the overproduction of hormones (mostly estrogen) that occurs during the early pregnancy  These estrogen hormones then circulate throughout the bloodstream and affect the body  Some doctors think that this excess of hormones causes the stomach to digest food more slowly, which results in the nausea and the vomiting  Stress and fatigue may also play a part in causing nausea and vomiting

24. Common Complications During The First Trimester  Serious complications that can harm either the mother or the baby occur in about a fifth of all pregnancies  There are other common complications that may cause alarm in the mother, but that typically do not impact the success of the pregnancy –For example:  Vaginal bleeding occurs in about 25% of pregnancies  Most cases this is not serious

25. A very risky time…  It is estimated that 10 percent of all recognized pregnancies spontaneously abort during the first trimester  The actual number of miscarriages is much higher  Perhaps fifty percent of all conceptions spontaneously result in miscarriage before the woman even knows that she is pregnant

26. Second Trimester: Middle Three Months  The second trimester of pregnancy encompasses weeks 14 through 27… –In the fetus:  Growth continues quickly from now until birth  Organs such as the heart and kidneys develop further  Eyebrows and fingernails form  The skin is wrinkled and covered with fine hair  periods of activity and quiet occur as the fetus moves, kicks, sleeps, and wakes  By the end of the second trimester, the fetus is about 11 to 14 inches long and weighs about 2 to 2 1/2 pounds  It can swallow, hear, and urinate

27. Middle Three Months: Preparing to Survive Heartbeat strongerHeartbeat stronger Digestive and excretory systems develop more fullyDigestive and excretory systems develop more fully Impressive brain growth (6X in size and responsive)Impressive brain growth (6X in size and responsive) -new neurons develop (neurogenesis) -synapses—connections between neurons (synaptogenesis)

28. Middle Three Months: Preparing to Survive Age of viability—age at which preterm baby can possibly survive (22 weeks)Age of viability—age at which preterm baby can possibly survive (22 weeks) -26 weeks survival rate about 50%. brain maturation critical to viability. weight critical to viability -28 weeks survival rate about 95%

29. Second Trimester: For the Mom  During the second trimester, continuing growth and development in mother and fetus cause many changes to occur: –Women may notice the following:  Their abdomen begins to swell. By the end of the second trimester, the uterus is near the rib cage.  The skin on the abdomen and breasts stretches. Stretch marks may be visible.  Movements made by the fetus. Known as quickening, this often occurs sometime around weeks 16 to 20.  A dark line forming from the navel down to the middle of the abdomen  Brown, uneven marks on the face or other changes in skin pigment  Darkening of the area around the nipples

30. No more morning sickness…  Often, the second trimester delivers a welcome energy boost to women and an end to morning sickness. It may also bring: –nasal congestion and occasional nose bleeds –whitish vaginal discharge –less of a need to urinate often –constipation –increase in appetite –Braxton Hicks contractions in which the uterus becomes hard and tight and then relaxes –leg cramps –backache –fatigue

31. Miscarriage is now at a much lower risk…  Miscarriage in low-risk pregnancies is rare at this time, but women sometimes have other problems in the second trimester, including: –High blood pressure –Sugar in the urine. This may be a sign of gestational diabetes, a form of diabetes associated with pregnancy –Iron-deficiency anemia

32. Final Three Months— Viability to Full Term  The third trimester of pregnancy generally spans weeks 28 through 40… Maturation of the respiratory and cardiovascular systemsMaturation of the respiratory and cardiovascular systems -critical difference Gains weight—4.5 lbs. in last 10 weeksGains weight—4.5 lbs. in last 10 weeks

33. Third Trimester  As the fetus gets bigger, it has less room to kick and stretch, so the movements felt by the mother may decrease  Fine body hair disappears  Most bones harden, but bones of the head stay soft and flexible for birth  As the time for birth approaches, the fetus usually moves down into the pelvis and settles into a good position  At 40 weeks, the fetus is considered full term. It is about 20 inches long and weighs 6 to 9 pounds

34. Risk Reduction  Despite complexity, most babies are born healthy  Most hazards are avoidable  Teratology—study of birth defects –teratogens—broad range of substances that can cause environmental insults that may cause prenatal abnormalities or later learning abilities

35. Determining Risk  Risk analysis—weighing of factors that affect likelihood of teratogen causing harm

36. Timing of Exposure Critical period—in prenatal development, the time when a particular organ or other body part is most susceptible to teratogenic damageCritical period—in prenatal development, the time when a particular organ or other body part is most susceptible to teratogenic damage -entire embryonic period is critical

37. Amount of Exposure  Dose and/or frequency  Threshold effect—teratogen relatively harmless until exposure reaches a certain level

38. Amount of Exposure Interaction effect—risk of harm increases if exposure to teratogen occurs at the same time as exposure to another teratogen or riskInteraction effect—risk of harm increases if exposure to teratogen occurs at the same time as exposure to another teratogen or risk

39. Genetic Vulnerability Genetic susceptibilities: product of genes combined with stressGenetic susceptibilities: product of genes combined with stress Folic-acid deficiency may cause neural- tube defectsFolic-acid deficiency may cause neural- tube defects -occurs most commonly in certain ethnic groups and less often in others Males are more genetically vulnerableMales are more genetically vulnerable

40. Specific Teratogens  No way to predict risk on an individual basis  Research has shown possible effects of most common and damaging teratogens  AIDS and alcohol extremely damaging –pregnant women with AIDS transmit it to their newborns; high doses of alcohol cause FAS; alcohol + drug use increase risk to developing organism

41. Low Birthweight  Low Birthweight (LBW) –less than 5 1/2 lbs.  grows too slowly or weighs less than normal  more common than 10 years ago  second most common cause of neonatal death  Preterm –birth occurs 3 or more weeks before standard 38 weeks

42.  Small for Gestational Age (SGA) –maternal illness –maternal behavior  cigarette smoking (25% of SGA births) –maternal malnutrition  poorly nourished before and during pregnancy  underweight, undereating, and smoking tend to occur together Low Birthweight

43.  Factors that affect normal prenatal growth –quality of medical care, education, social support, and cultural practices Low Birthweight

44. Third Trimester: For the Mom  Women may notice the following: –Movements of the fetus can be felt more strongly –Abdominal pain that may or may not be true labor pains –Shortness of breath because the uterus is pushing against the diaphragm. The diaphragm is a flat, strong muscle that aids in breathing. Towards the end of the third trimester, the baby may drop down into a lower position. This will make it easier for the mother to breathe –A need to urinate more often when the baby drops down into a lower position in the pelvis –Yellow, watery fluid leaking from her nipples, known as colustrum –Her navel sticking out

45. Third Trimester: For the Mom  During the third trimester, certain discomforts and mood changes may occur: –fatigue or extra energy, or alternate periods of both –increasingly heavy white vaginal discharge –more mild lower abdominal pains with uterine tightening and then relaxing –more or less of an appetite –constipation, heartburn, indigestion, gas, and bloating –headaches, dizziness, or faintness –more trouble sleeping –itchy abdomen –varicose veins –swelling of the legs, feet, and hands –increasing clumsiness as shape and balance changes –anxiety, impatience, and restlessness –irritability and unusual sensitivity

46. The Birth Process  Hormones in mother’s brain signals process  Contractions begin: strong and regular at 10 minutes apart –average labor for first births is 8 hours

47.  Assessment—Apgar scale –five factors, 2 points each  heart rate  breathing  color  muscle tone  reflexes  score of 7 or better: normal  score under 7: needs help breathing  score under 4: needs urgent critical care The Newborn’s First Minutes

48. Variations  Parents Reaction –preparation for birth, physical and emotional support, position and size of fetus, and practices of mother’s culture  Medical Attention –birth in every developed nation has medical attention –22% of births in U.S. are cesarean section  removal of fetus via incisions in mother’s abdomen and uterus –is medical intervention always necessary?

49. Birth Complications  Cerebral Palsy –brain damage causing difficulties in muscle control, possibly affecting speech or other body movements  Anoxia –lack of oxygen that, if prolonged, can cause brain damage or death

50. First Intensive Care... Then Home  At the Hospital –many hospitals provide regular massage and soothing stimulation; ideally, parents share in caregiving  At Home –complications, e.g., minor medical crises –cognitive difficulties may emerge, but high- risk infants can develop normally

51.  Strong family support  Fathers play a crucial role –may help wives abstain from drugs or alcohol –can reduce maternal stress  Parental alliance—commitment by both parents to cooperate in raising child –helps alleviate postpartum depression Mothers, Fathers and a Good Start

52.  Parent-infant bond—strong, loving connection that forms as parents hold, examine, and feed their newborn –immediate contact not needed for this to occur Mothers, Fathers and a Good Start