The embryos systems and those of the mother o if two

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the embryo’s systems and those of the mother o If two different ova are fertilized by two different sperms, the result is fraternal twins o Identical twins result when a fertilized ovum subsides before it implants in the uterus o Problems with Implantation ¾ fail to implement 1/7 miscarriage Ectopic pregnancy : the implantation of a fertilized egg outside of the endometrium of the uterus Tubes may burst Pregnancy The First Trimester-The Mother o Pregnancy tests work by determining if a hormone HCG is present in women’s urine o HCG prevents the corpus luteum from atrophying, thus keeping progesterone (the hormone maintaining the endometrium) level high o Most common early pregnancy symptom is morning sickness o Couvade syndrome: the experiencing of pregnancy symptoms by male partners; sometimes called “sympathy pains” The First Trimester- The Embryo/Fetus o Embryo : the term given to the blastocyst after it has implanted o Cell differentiation begins to take place now, and development occurs in orderly ways o Three inner cell layers will form specific parts of the body o Ectoderm forms nervous system, skin and teeth o Mesoderm forms muscles, skeleton and blood vessels o Endoderm forms the internal organs (lungs, liver, digestive system) o After 8 weeks and until birth, the developing organisms is called fetus The Second Trimester-The Mother o Movement can only be felt by its mother o Quickening: the first time a pregnancy woman experiences movement of the fetus, usually in the 5 th month o Stretch marks o Water retention The Second Trimester- The Fetus o Sucking motions o Detectable heartbeat o Respond to sound o Sleep and wakefulness o 6 th month the fetus can open its eyes The Third Trimester- The Mother o Pack pain, pressure on the bladder, indigestion, heartburn, gas, constipation Downloaded by breanna baric ([email protected]) lOMoARcPSD|3232224
The Third Trimester- The Fetus o By the end of the 7 th month, the fetus is about 15 inches long and weighs 1.5 pounds o Fatty tissue develops o The fetus is covered with light hair (lanugo) and waxy bluish substance (vernix caseosa) Sexual Intercourse During Pregnancy o Steady decline in sexual activity throughout pregnancy o Associated with hormones o Women feel they no longer look attractive o Physical discomfort o Fear the safety of the fetus Complications of Pregnancy 97% of all births result in healthy, normal infants Teratogens : substances that can harm an embryo or fetus Critical periods : in relation to teratogens, the time during embryonic or fetal development during which a particular part of the body is most susceptible to damage Smoking o Associated with low birth weight o Increases in miscarriages, ectopic pregnancies, infant mortality, preterm birth Alcohol o Physical deformities o Fetal alcohol syndrome (FAS) : a condition common to infants born to alcoholic mothers, involving physical and nervous system abnormalities o Maximum effect on the developing fetus in the 3 rd week of pregnancy

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