Prenatal Development PDF

Fetal development Fertilization Only one sperm can fertilize an ovum Sperm carry genetic material necessary for reproduction Twins Monozygotic twins/identical twins Same o Always ______ sex and highly similar in physical appearance Dizygotic twins/fraternal twins o May be of different sexes 3 First...

Fetal development Fertilization Only one sperm can fertilize an ovum Sperm carry genetic material necessary for reproduction Twins Monozygotic twins/identical twins Same o Always ______ sex and highly similar in physical appearance Dizygotic twins/fraternal twins o May be of different sexes 3 First Trimester (1-3 months) 1) The germinal period (weeks 1-2) Implantation: Zygote travels out of the fallopian tube and implants in the uterine wall 2) The embryonic period (weeks 3-8) (胚胎期) Organogenesis: The groundwork for all body structures and internal organs formed About 1 inch Placenta (胎盤) Sensitivity to teratogens (e.g., viruses/medicines/alcohol etc): malformations in the fetus (胎兒) 3) The fetal period (weeks 9-38) – it lasts till birth The fetus grows to 3 inches in the 3rd month Changes in the sex organs (12th week) Sex hormones make male brain and female brain slightly different (e.g., hypothalamus, amygdala, hippocampus) 7 Second Trimester (4-6 months) The fetus grows to 10 inches and increases to around 2 pounds Quickening (approx. 17-20 weeks) Developing fetus has grown large enough that its movements can be felt by the mother End of 6th month, sensory receptors of the fetus are well established 9 Source: http://www.mamayurveda.com/blog/ayurvedic-overview-second-trimester Third Trimester (7-9 months +) Fetus grows from 10 to 20 inches and increases from 2 to 7.5 pounds By 32 weeks, critical level of neurological maturation is achieved At the end of the third trimester: The fetal brain produces hormones triggering the birth process 10 Sex differences in prenatal development Girls Slightly faster skeletal development (4-6 weeks ahead) Boys Slightly heavier and longer at birth More muscle tissue, fewer fat Slightly more active before birth More X chromosome-related problems 11 Low birth weight Different types (a range) Low birth weight (LBW) (Below 2500 grams (5.5 pounds) Very low birth weight (VLBW)(Below 1,500 grams (3.3 pounds) Extremely low birth weight (ELBW)(Below 1,000 grams (2.2 pounds) Causes 38 weeks born before _________of gestation [=period of pregnancy] (Preterm infant) Completed 38 weeks of gestation with unexpected low birth weight (Small-for-date infant, i.e. lighter than usual) Consequences lower levels of responsiveness at birth and in the early months of life suffer from respiratory distress syndrome due to poorly developed lung 12 Impact of pregnancy (1) The impact of the fetus on the pregnant woman Pregnancy alters a woman’s body image and sense of well-being Changes in roles and social status E.g., fewer responsibilities in workplace, or may be viewed as an annoyance (e.g. frequent absenteeism) E.g., being treated with great concern and care in family E.g., change of social roles in the family, e.g. mother/father  grandmother/grandfather; sisters/brothers  aunts/uncles Any differences across cultures? 熏 13 Impact of pregnancy (1) The impact of the fetus on the pregnant woman Changes in emotional state Anxiety and depression; or excitement and hopefulness Physical changes become a source of stress o E.g., nausea, being tired, indigestion, worrying the health and care of the new baby Prenatal depression and postpartum depression 14 Impact of pregnancy (2) The impact of the pregnant woman on the fetus Factors affecting the fetus Poverty Mother’s age ______________ Drug use o Nicotine o Alcohol o Caffeine …(more details in your textbook) 15