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Complications of Pregnancy

Outline

A. Physiology of Pregnancy

    1. Changes in Reproductive system

        A. Uterus

            a. growth- myometrium becomes more compliant, weight
            increases 20 fold

            b. position - can lead to supine hypotensive syndrome

            c. contractility

                     oxytocin

Braxton Hicks contractions - painless contractions, irregular and sporadic beginning about 6 th week of gestation

            d. endometrium

                        inadequate luteal phase disorder

        B. Cervix

            a. Chadwick's sign

        C. Ovaries

        D. Vagina

        E. Breasts

          a. estrogen and progesterone- growth of ductal and alveolar systems

   b. prolactin - required for final steps of labula alveolar maturation, necessary for milk production, inhibited by PIF (prolactin inhibitory factor). Suckling of child at breat inhibits PIF, allowing for prolactin release           

c. oxytocin - necessary for reflex that causes ejection of milk from nipples- stimulated by baby's suckling, may beome conditioned to other stimuli

    2. Cardiovascular system

        A. Heart- pushed up and left, may cause systolic murmurs

B. Blood volume- by end of 2nd trimester increased by 50%, causes   HCT to decrease = physiological dilutional anemia of pregnancy

        C. Cardiac Output - increases 30 - 50% above normal

        D. Heart Rate- increases, typically,   from 70 to 78 (1st trimester) to  85 (at term)

    3.Respiratory system

        a. TV increases from 500 - 700

        b. oxygen consumption increases by 14%

    4. Urinary system

        a. hydroureter- retention of water and sweling of tissue

        b. uterus pushes bladder forward and upward

        c. GFR increases 30 -50%

        d. fluid retention

B.At Risk Pregnancy

    1. Nausea and vomiting

        a. morning sickness

b. hyperemesis gravidarum - vomiting severe enough to cause   electrolyte, metabolic and nutritional problems

    2. Multiple gestation

        a. identical twins = 1/200 births, fraternal twins = 1/80 births

b. mother of twins at increased risk for
      preeclampsia
      anemia
      hypertension
      placenta previa
      prematurity
      postpartum hemmorhage

c. transfusion syndrome ( in identical twins)

    3. Anemia

a. 56% of all pregnant woman have some degree of anemia

b. Iron deficiency anemia and Folic acid deficiency anemia

    4. Hemoglobinapathies

        a. beta thalassemia minor

        b. sickle cell disease

        c. G6PD deficiency

    5. Rh blood incompatibilities

        a. erthroblastosis fetalis

        b. use of Rhogam

    6. Incompetent Cervix

C. First Trimester Bleeding

    1.abortion

        a. incomplete

        b. complete

        c. missed

    2.Ectopic pregnancy

        a. accounts for 12% of maternal mortality

    3. Hydatiform mole ( a developmewntal anomaly of the placenta)

        a. 1/2000 births in US, more frequent in Asia, south Pacific
        and Philipines

        b. 85% of cases mole is benign

C. Second Trimester Bleeding

        a. as many as 155 of spontaneous abortions occur in 2nd trimester

        b. placenta previa (abnormal implantation of placenta)

                1. incidence is 1/300 deliveries

D. Third Trimester Bleeding

        a. abruptio placentae (separation of placenta from uterine surface
                before delivery of the infant)

        b. mild, moderate or severe

        c. maternal mortality rate = 5%, infant mortality rate = 25- 50%

E. Preterm and Post term Labor

    a. preterm = any delivery between 20 - 37th week, 10% of all woman

    b. post term = delivery after 42nd week, 5- 8% of all woman

    c. use of tocalytic drugs

F. Hypertensive Disorders of Pregnancy

    a. PIH (pregnancy induced hypertension, or pre-eclampsia)

a. incidence = 6%, primigravidas 6-8x more likely to develop then
multiparas

b. diagnosed by the triad of
                HTN
                Proteinuria
                Edema

    b. Eclampsia (seizures secondary to PIH)

Discussion  

    In a real sense pregnancy is nature's version of transplantation.   The prostate produces seminal fluid which can block  inflammation. This allows sperm cells to make it all the way to the Fallopian tubes. Once in the Fallopian tubes an immunological response kills nearly all the sperm cells, but not quite fast enough- at least one sperm succeeds in fertilization. After fertilization immune responses then " mop up" all the remaining sperm in the Fallopian tubes. This results in an inflammatory reponse which causes the Fallopian tubes to narrow. This narrowing actually is adaptive, since it prevents the fertilized egg from tumbling down the Fallopian tubes to the utereus too quickly, allowing sufficient time for the final preparation for implantation of the fertilized egg. It is speculated that if the sperm is not antigenic enough  then there is no immune reponse, folowed by inflammation and , hence, the egg is lost- a possible cause of infertility.
    Once the egg is implanted a furious atttack is launched to try to dislodge it, but the placenta prevents T cells from crossing (if this membrane is destroyed then a miscarriage will result). The fetus's T cells, meanwhile, are secreting suppressor chemical which can cross the placenta into the mother's blood and suppress her T cells. This can actually be of great benefit to a mother who suffers from an autoimmune disease. For example, women with lupus often have a remission during pregnancy. Male babies face even a greater immune threat since they conatina a marker (Y chromosome) never before seen by the mother. More spontaneously aborted fetuses are male then female. antibodies can cross the placenta but the placenta displays a certain "intelligence". It mostly prevents harmful antibodies from crossing and only allows antibodies helpful to the fetus to
cross.

Clinically  

    Any bleeding that occurs during pregnancy should be taken seriously since it can be one of numerous different problems. All women who are pregnant should be encouraged to be tested for HIV. The reason for this is that  a. many people who are HIV positve are unaware of it and b. should a woman test positive, she can be treated with zidovudine. Clinical trials have shown that treatment with zidovudine during pregancy in HIV + woman can dramatically decrease the risk of in utero infection of the fetus. There does not seem to be any adverse effects on infants so treated.