PSYCH 230 1st Edition Lecture 19 Outline of Last Lecture I. Models of Sexual Orientation: Who is Homosexual?II. Measuring Sexual Orientation: How Prevalent?III. Why Are There Different Sexual Orientations?IV. Biological TheoriesV. Developmental TheoriesVI. Behaviorist TheoriesSociological TheoriesVII. Interactional TheoriesOutline of Current Lecture Pregnancy and BirthI. Statistics and Current TrendsII. ConceptionIII. Early Signs of PregnancyIV. Pregnancy Testing Current LectureI. Statistics and Current Trendsa. In 2009, 4,131,019 registered births in U.S., 3% lower than 2008b. Teen births (ages 15-19) lowest level since 1940c. Average age of first-time mother in the U.S. increased by almost 4 years—from 21.4 to 25-years old from 1920 to 2006d. In 2006, 1 in 12 births was a first birth to women 35 and olderII. Conception a. Our bodies are designed to promote pregnancyb. During ovulation:c. A woman’s sexual desire peaks d. A mucus plug in the cervix disappearse. Cervical mucus thins & creates gaps that vibrate with the sperm to aid motility and trap defective sperm; filters bacteria from semenf. Female orgasm pushes semen to the uterus and toward the Fallopian tubesg. Semen thickens upon ejaculation to stay in the vagina for 20 minutes to aid sperm travelThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.h. Pregnancy is also complexi. Many sperm are killed by the female’s immune systemj. Many pregnancies end in spontaneous abortionk. The ovum can live for 24 hoursl. Sperm can live for 72 hours; less than 1% can live up to one weekm. Pregnancy may occur a few days before or after ovulationn. The ovum may release chemicals to signal its locationo. If a sperm reaches the ovum, it wriggles violentlyp. After implantation, the blastocyst divides into two layers, the endoderm & ectoderm, followed shortly by the mesodermq. Embryo – developing cell mass of 2–8 weeksr. Amnion – membrane covering the embryo that fills with protective fluids. Placenta – attached to the uterine wall, it aids the fetus in respiration, nutrition, excretiont. Umbilical cord – connects fetus to placentau. Multiple births occur in 1 out of 50 couplesv. Fraternal twins – two ova are released & fertilized; 2/3 of twins are fraternal; dizygoticw. May be inherited from the mothersx. More likely with women over 30y. Identical twins – single zygote divides into 2 separate zygotes; monozygoticz. Siamese twins – fail to completely separateIII. Early Signs of Pregnancya. Missing a period, or maybe some spottingb. Breast tenderness, frequent urination, food aversionsc. Morning sickness- 50–80% of pregnant women experience nausea &/or vomiting, any timeof the day- Due to increased estrogen & progesterone irritating the stomach lining- May protect the fetus from illnessd. Pseudocyesis – false pregnancy- May have a physical cause- Most cases have a psychological cause- More common in women who believe childbearing is central to their identity, have a history of infertility &/or depression, have had a miscarriagee. Expectant fathers can also experience this, as well as couvadeIV. Pregnancy Testinga. Over-the-counter pregnancy tests- Can be less expensive at a clinic- The tests measure for human chorionic gonadotropin (hCG), which is made by placental cellsb. Detection in blood or urine can occur 8 to 9 days after ovulationc. hCG levels peak in the 2nd & 3rd monthsd. May be inaccurate if tested too soon or after the 12th weeke. False positives may occur with kidney disease, kidney infection, overactive thyroid, large doses of tranquilizers, aspirin, antidepressants, anticonvulsantsf. Radioimmunoassay (RIA) blood tests are the most accurate, can detect hCG within a few days after conceptiong. Due date – calculated from the first day of the last menstrual periodh. Naegeles rule – subtract 3 months from the first day of the last period and add 7 days for a single birth- Rule is most accurate for women with 28-day