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Bio 27 November 7, 2012 Chapter 11: Conception, Pregnancy, and Childbirth.

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Presentation on theme: "Bio 27 November 7, 2012 Chapter 11: Conception, Pregnancy, and Childbirth."— Presentation transcript:

1 Bio 27 November 7, 2012 Chapter 11: Conception, Pregnancy, and Childbirth

2 Why not to have children Expensive Time-consuming Lack of freedom Cause marital stress & dissatisfaction Prevent career advancement, especially for women Dump coffee on your iPhone

3 Why to have children


5 Enhancing the possibility of conception The 6-day window that ends on the day of ovulation is the most fertile time Sperm can live in the uterus for days or weeks Ovulation predictor tests are available Basal body temperature is not a good PREDICTOR of ovulation

6 Trying to conceive 60% of couples trying to conceive succeed within 3 months After 6 months of trying, you are encouraged to see a doctor – Both partners should be checked; 40% of infertility cases involve the male partner, 40% involve the female partner, and 20% involve both About 12% of couples attempting pregnancy have problems – This number is going up as more older people try to have kids

7 Infertility Infertility or difficulty conceiving can be extremely painful for individuals and couples People may assume that they don’t want children A couple’s relationship can be damaged by the stress of infertility

8 Female infertility: ovulation problems Problems with ovulation account for 20% of infertility Age and female fertility are strongly linked – female fertility peaks at age 20–24 – rapidly decreases at age 30 – women over 35 are twice as likely to have unexplained infertility as younger women Ovulation problems can be caused by diet, genetics, stress, being underweight, smoking, and other medical conditions Drugs can promote ovulation

9 Female infertility: other problems A woman’s cervical mucus can contain antibodies that attack her partner’s sperm Cervical mucus can also form an impenetrable plug, preventing sperm from passing through the cervix Infections of the female reproductive tract may scar these organs; may be caused by sexually transmitted infections May also have genetic malformation of reproductive tract

10 Male infertility Male infertility is most often caused by low sperm count, or abnormal sperm shape or motility Can be caused by STIs, drug use, and diseases such as mumps Hot baths, tight clothing, and long bike rides (really!) can also impair sperm production


12 Reproductive alternatives Artificial insemination: mechanical introduction of semen into the vagina – Can be done at home – Can help if have a low sperm count or if no male partner Surrogate mothers: a woman willing to be artificially inseminated and carry the child to term – 1000 surrogate births in the U.S. in 2007, up from 260 in 2006 – Laws on paying surrogates vary by state

13 Assisted reproductive technology First “test tube baby” born in 1978 in England More than 2 million children have now been conceived through in vitro fertilization (IVF) – Woman is treated with hormones to cause multiple eggs to be released per cycle – Eggs are removed from ovary and fertilized by partner’s sperm in a laboratory dish – One or more embryos are then placed in the woman’s uterus – Can also be done with donor eggs – Excess embryos can be frozen

14 Costs and risks of assisted reproductive technologies One round of IVF costs $12,000–14,000 and is typically not covered by insurance; each round has a 50–72% success rate Donor eggs or sperm may increase the cost Some choose to increase chances of success by having multiple embryos implanted, raising the incidence of multiple births Higher overall risk of birth defects with IVF, for unknown reasons

15 Pre-implantation screening & other ethical questions IVF allows for screening of embryos for genetic traits before implantation Can select male or female embryos by looking at sex chromosomes Some genetic disorders can be diagnosed pre- implantation “Leftover” embryos may be donated for stem cell research IVF also enables pregnancy in much older women

16 Detecting pregnancy The hormone human chorionic gonadotropin is made at high levels in the bodies of pregnant women and can be detected in the blood and urine around the time of the first missed period Home tests can yield false positive or false negative results


18 Miscarriage and stillbirth A spontaneous abortion happening in the first 20 weeks of pregnancy is a miscarriage; one happening in the last 20 weeks is a stillbirth Early miscarriages may occur before a woman even knows she is pregnant Having one miscarriage does not raise chances of having additional ones, but multiple miscarriages can be indicative of problems

19 Most common causes of miscarriage: Chromosomal abnormality Maternal age >35 years More than 5 alcoholic drinks per week More than 375 mg caffeine per day (2–3 cups coffee) Cocaine use Damaged cervix Chronic kidney inflammation Abnormal uterus Infection Underactive thyroid gland Autoimmune reaction Diabetes Emotional shock Aspirin and ibuprofen use in early pregnancy Obesity

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