ECD 51 Chapter 4 Genetics, Prenatal Development, and Birth

GENETIC INFORMATION Ancestral information is carried in DNA DNA molecules form genes Some are dominant Some are recessive Genes are arranged along chromosomes Typical cells:23 pairs Chromosomes are in all human cell nuclei Sperm and ovum (gametes) each contain 23 chromosomes

THE GENETIC BEGINNINGS OF DEVELOPMENT sperm from father (x or y chromosomes) + ovum from mother (x chromosomes only) = New person contains 46 chromosomes either male (xy) or female (xx)

TWINS Fraternal twins = 2 ovum + 2 sperm = 2 different zygotes Each has different genetic material Identical twins = 1 ovum + 1 sperm = 1 zygote that divides into 2 Both have the same genetic material Twins = 2% of births (2/3 are fraternal)

Chromosomal and Genetic Abnormalitie Down syndrome: 3 #21 chromosomes instead of usual 2 most common cause of mental retardation Fragile X syndrome brittle or separated X chromosome infantile autism Turner’s syndrome only X chromosome, physical malformation and sterility

Klinefelter’s syndrome XXY chromosomes, sterility, general physical and mental health Huntington disease genetic miscode, fatal central nervous system Hemophilia limits blood clotting Rh disease baby’s Rh+ blood attacked by Rh+ antibodies from Rh- mother

CULTURAL DIFFERENCES RELATED TO GENETICS “nature and nurture interact in complex ways” Cultural differences have been found in: motor activity height weight hereditary diseases: sickle-cell anemia (African descent) cystic fibrosis (Caucasian) Tay-Sacks (Eastern European)

PRENATAL DEVELOPMENT Activity Get in groups of 4-5 Find pictures in the envelopes Guess the number of weeks or months of the embryo/fetus shown in the pictures Use your book (chapter 4) to help you with your answers

MAJOR STAGES OF PRENATAL DEVELOPMENT Ovum: Conception  2 weeks rapid cell differentiation implantation in uterus (10 days after conception) most at risk for miscarriage Embryo: 2 weeks  8 weeks almost all major organs and structures form placenta / umbilical cord / amnion environmental influences are great Fetus: 8 weeks  birth rapid growth, refining, improving and getting more complex of what is already there nervous, blood and breathing systems open/close eyes, swallows, hiccups, sucks turning at 16 weeks last 3 months, brain and spinal column develop maternal nutrition and health important

ENVIRONMENTAL INFLUENCES ON PRENATAL DEVELOPMENT DRUG USE DURING PREGNANCY Heroin: premature birth, physical malformations, respiratory difficulties, lower birth weight, greater risk of death at birth, addiction at birth causes withdrawal symptoms Cocaine/crack (fastest growing problem in U.S.):risk of miscarriage, premature birth, brain damage, low birth weight, physical malformations

Smoking miscarriage, premature birth, low birth weight smoking by fathers hurts babies, too damage is long-term implicated in sudden infant death syndrome Alcohol any use can be detrimental to baby heavy use causes fetal alcohol syndrome nervous system impairment, mental retardation, hyperactivity, deficiencies in height, weight, brain size Medications can cause problems for unborn child examples: aspirin, tetracycline, Valium Prescription drugs example: DES (diethilstillbestrol, prescribed from ) had negative effects that only showed up in adolescence (vaginal cancer, miscarriages, genital abnormalities)

MATERNAL NUTRITION AND HEALTH Malnourished mother = malnourished baby infant brains are most vulnerable Maternal illness can hurt babies rubella / HIV Cultural gaps in health status are due primarily to poor prenatal care comprehensive social programs needed to offset economic barriers cultural sensitivity critical in some cases

CHILDBIRTH

STAGES OF LABOR Dilation ∙ longest stage of labor – hrs / 4-6 hrs ∙ regular contractions of uterus dilate (stretch) cervix ∙ amnion breaks to let out amniotic fluid ∙ cervix stretches over head in transition period Expulsion of the fetus ∙ shorter period – ½-1 hour ∙ urge to push and contractions push baby out Expulsion of the placenta ∙ shortest period – 5-10 minutes ∙ placenta detaches from uterus and is expelled

Childbirth itself can affect children’s development. Birthing practices vary across cultures. Almost all cultures consider childbirth to be a joyful experience in which mothers are prepared, educated, and supported.