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 recessiveGenes are arranged along chromosomesTypical 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 zygotesEach has different genetic material

Identical twins =1 ovum + 1 sperm = 1 zygote that divides into 2Both 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 2most common cause of mental retardation

Fragile X syndromebrittle or separated X chromosomeinfantile autism

Turner’s syndrome only X chromosome, physical malformation and

sterility

Klinefelter’s syndromeXXY chromosomes, sterility, general physical and mental health

Huntington diseasegenetic miscode, fatal central nervous system

Hemophilia limits blood clottingRh 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 activityheightweighthereditary diseases:

sickle-cell anemia (African descent)cystic fibrosis (Caucasian)Tay-Sacks (Eastern European)

PRENATAL DEVELOPMENT

ActivityGet in groups of 4-5Find pictures in the envelopesGuess the number of weeks or months of the

embryo/fetus shown in the picturesUse your book (chapter 4) to help you with your

answers

MAJOR STAGES OF PRENATAL DEVELOPMENT

Ovum: Conception 2 weeksrapid cell differentiationimplantation in uterus (10 days after conception)most at risk for miscarriage

Embryo: 2 weeks 8 weeks almost all major organs and structures formplacenta / umbilical cord / amnionenvironmental influences are great

Fetus: 8 weeks birthrapid growth, refining , improving and getting more complex of what is already therenervous, blood and breathing systemsopen/close eyes, swallows, hiccups, sucksturning at 16 weekslast 3 months, brain and spinal column developmaternal 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 weightsmoking by fathers hurts babies, toodamage is long-termimplicated in sudden infant death syndrome

Alcoholany use can be detrimental to babyheavy use causes fetal alcohol syndrome

nervous system impairment, mental retardation, hyperactivity, deficiencies in height, weight, brain size

Medications

can cause problems for unborn childexamples: aspirin, tetracycline, Valium

Prescription drugs example: DES (diethilstillbestrol, prescribed from 1945-1970) had negative effects that only showed up in adolescence (vaginal cancer, miscarriages, genital abnormalities)

MATERNAL NUTRITION AND HEALTH

Malnourished mother = malnourished babyinfant brains are most vulnerable

Maternal illness can hurt babiesrubella / HIV

Cultural gaps in health status are due primarily to poor prenatal care

comprehensive social programs needed to offset economic barrierscultural sensitivity critical in some cases

CHILDBIRTH

STAGES OF LABORDilation

∙ longest stage of labor – 12-14 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.