Bio 27 November 7, 2012

Bio 27 November 7, 2012

Chapter 11: Conception, Pregnancy, and Childbirth

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

Why to have children

HOW TO MAKE BABIES

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

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

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

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

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

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

REPRODUCTIVE ALTERNATIVES

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

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

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

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

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

SPONTANEOUS AND ELECTIVE ABORTION

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

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