question: Why do women get sick during pregnancy?
comment: Friendly OB/GYN here! ;-) During pregnancy, the fetus -- or more specifically, the placenta -- makes a hormone called **hCG** (human chorionic gonadotropin). This is a beautiful little chemical that helps to keep the uterus a good environment to sustain the pregnancy. If it weren't for the hCG, mom's uterus would shed its contents, she'd get her period, and the pregnancy would end. This hCG gets into mom's blood and urine, and it's also what we look for when we do pregnancy tests. Unfortunately, hCG in the blood has some nasty side effects for mom. The hCG causes the ovaries to release more estrogen, which itself can cause nausea. The good news is that hCG levels begin to drop after the first trimester, and so the nausea tends to go away at that point, too.
passages: Section::::Bacterial vaginosis and pregnancy.
  
  Bacterial vaginosis in pregnancy is an alteration of the normal vaginal microbiota of pregnancy. Intrauterine infections in pregnancy are caused by bacteria that cause inflammation. The women may experience few or no symptoms. This sometimes leads to chorioamnionitis and other negative pregnancy outcomes. When there are high bacterial counts in of the vagina during pregnancy is typically due to the presence of the following organisms:
  
  BULLET::::- "G. vaginalis"
  
  BULLET::::- "F. nucleatum"
  
  BULLET::::- "Staphylococci spp"
  
  BULLET::::- "Streptococci"
  
  BULLET::::- "Atopobium vaginae"
  
  BULLET::::- "Mobiluncus spp"
  
  BULLET::::- "Mycoplasma" spp
  
  BULLET::::- Bacteroides ureolyticus
  
  BULLET::::- "Fusobacterium"
  
  Section::::History.
   The embryo and fetus have little or no immune function. They depend on the immune function of their mother. Several pathogens can cross the placenta and cause (perinatal) infection. Often microorganisms that produce minor illness in the mother are very dangerous for the developing embryo or fetus. This can result in spontaneous abortion or major developmental disorders. For many infections, the baby is more at risk at particular stages of pregnancy. Problems related to perinatal infection are not always directly noticeable.
  
  The term TORCH complex refers to a set of several different infections that may be caused by transplacental infection.
   Susceptibility and severity of infections in pregnancy
  
  In pregnancy, there is an increased susceptibility and/or severity of several infectious diseases. 
  
  Section::::General determinants.
  
  There are several potential risk factors or causes to this increased risk:
  
  BULLET::::- An increased immune tolerance in pregnancy to prevent an immune reaction against the fetus
  
  BULLET::::- Maternal physiological changes including a decrease in respiratory volumes and urinary stasis due to an enlarging uterus.
  
  BULLET::::- The presence of a placenta for pathogens to use as a habitat, such as by "L. monocytogenes" and "P. falciparum".
  
  Section::::Examples.
   The embryo and fetus have little or no immune function. They depend on the immune function of their mother. Several pathogens can cross the placenta and cause (perinatal) infection. Often, microorganisms that produce minor illness in the mother are very dangerous for the developing embryo or fetus. This can result in spontaneous abortion or major developmental disorders. For many infections, the baby is more at risk at particular stages of pregnancy. Problems related to perinatal infection are not always directly noticeable.
  
  Section::::Routes.:During childbirth.
   If a mother is infected with a disease, the placenta cannot always filter out pathogens. Viruses such as rubella, chicken pox, mumps, herpes, and human immunodeficiency (HIV) are associated with increased risk of miscarriage, low birth weight, and prematurity, physical malformations, and intellectual disabilities. The human immunodeficiency virus can lead to acquired immune deficiency syndrome (AIDS). Untreated HIV infected expectant mothers pass the virus to their developing offspring between 10 and 20 percent of the time. . Expectant mothers infected with bacterial or parasitic diseases may also pass the diseases on to the fetus. Examples of diseases include chlamydia, syphilis, tuberculosis, malaria, and toxoplasmosis. One of the most common of these diseases is toxoplasmosis. A pregnant female may become infected through contact with contaminated soil, such as through gardening, eating raw or undercooked meat or unwashed vegetables or fruits, or contact with the feces of infected cats. If the exposure occurs during the first trimester, eye and brain damage may result. Exposure later in pregnancy may result in mild visual and cognitive impairments. 
   In pregnancy, changes in the levels of female sex hormones, such as estrogen, make a woman more likely to develop candidal vulvovaginitis. During pregnancy, the "Candida" fungus is more prevalent (common), and recurrent infection is also more likely. There is no clear evidence that treatment of asymptomatic candidal vulvovaginitis in pregnancy reduces the risk of preterm birth. Candidal vulvovaginitis in pregnancy should be treated with intravaginal clotrimazole or nystatin for at least 7 days.
  
  Section::::Infections.:Bacterial vaginosis.
   The recent identification of the presence of microorganisms in maternal-infant body fluids that were previously thought to be sterile has provided one explanation for the presence of the inflammatory response in both the mother and infant. Sixty-one percent of pregnant women with chorioamnionitis, or inflammation of the amniotic fluid, were found to be infected by microorganisms. Often, more than one pathogen was present. In fifteen percent of pregnant women inflammation was still evident even though there was no evidence of pathogens. This may indicate that there are other causes. A high percentage, 51% to 62%, of pregnant women who had chorioamnionitis also had inflammation of the placenta.
   A pregnant woman is more susceptible to certain infections. This increased risk is caused by an increased immune tolerance in pregnancy to prevent an immune reaction against the fetus, as well as secondary to maternal physiological changes including a decrease in respiratory volumes and urinary stasis due to an enlarging uterus. Pregnant individuals are more severely affected by, for example, influenza, hepatitis E, herpes simplex and malaria. The evidence is more limited for coccidioidomycosis, measles, smallpox, and varicella. Mastitis, or inflammation of the breast occurs in 20% of lactating individuals.
   BULLET::::- Hyperemesis gravidarum, excessive nausea and vomiting that is more severe than normal morning sickness.
  
  BULLET::::- Pulmonary embolism, a blood clot that forms in the legs and migrates to the lungs.
  
  BULLET::::- Acute fatty liver of pregnancy is a rare complication thought to be brought about by a disruption in the metabolism of fatty acids by mitochondria.
  
  There is also an increased susceptibility and severity of certain infections in pregnancy.
  
  Section::::Intercurrent diseases.
   Bacterial vaginosis is an imbalance of naturally occurring bacterial flora in the vagina. Bacterial vaginosis as an intercurrent disease in pregnancy may increase the risk of pregnancy complications, most notably premature birth or miscarriage. However, this risk is small overall and appears more significant in women who have had such complications in an earlier pregnancy.
  
  Section::::Valvular heart disease.
  
  In case of valvular heart disease in pregnancy, the maternal physiological changes in pregnancy confer additional load on the heart and may lead to complications.
   Pregnancy alters the vaginal microbiota with a reduction in species/genus diversity.
  
  Physiological hydronephrosis may appear from six weeks.
  
  Section::::Gastrointestinal.
   A common feature of immune factors in causing recurrent pregnancy loss appears to be a decreased maternal immune tolerance towards the fetus.
  
  Section::::Causes.:Immune factors.:Antiphospholipid syndrome.
   A number of maternal infections can lead to a single pregnancy loss, including listeriosis, toxoplasmosis, and certain viral infections (rubella, herpes simplex, measles, cytomegalo virus, coxsackie virus). However, there are no confirmed studies to suggest that specific infections will lead to recurrent pregnancy loss in humans. Malaria, syphilis and brucellosis can also cause recurrent miscarriage.
  
  Section::::Causes.:Chronic endometritis.
   Section::::Hypercoagulability.
  
  Hypercoagulability in pregnancy is the propensity of pregnant women to develop thrombosis (blood clots). Pregnancy itself is a factor of hypercoagulability (pregnancy-induced hypercoagulability), as a physiologically adaptive mechanism to prevent "post partum" bleeding. However, when combined with any additional underlying hypercoagulable state, the risk of thrombosis or embolism may become substantial.
  
  Section::::Infections.
  
  Section::::Infections.:Vertically transmitted infections.
  
  Many infectious diseases have a risk of vertical transmission to the fetus. Examples include: 
  
  BULLET::::- Chickenpox
  
  BULLET::::- Chlamydia
  
  BULLET::::- Herpes simplex or Neonatal herpes simplex
  
  BULLET::::- HIV
  
  BULLET::::- Human T-lymphotropic virus
  
  BULLET::::- Syphilis
   BULLET::::4. Infection: each person has a different immune system, when a woman is pregnant, their immune systems behaves different than originally causing increased susceptibility to infection which can be threatening to both mother and baby. Different types of infection include, infection of amniotic fluid and surrounding tissues, influenza, genital tract infections, and sepsis/blood infection. Fever, chills, abnormal heart rate, and breathing rate can indicate some form of infection.
   Babies can also become infected by their mother during birth. During birth, babies are exposed to maternal blood and body fluids without the placental barrier intervening and to the maternal genital tract. Because of this, blood-borne microorganisms (hepatitis B, HIV), organisms associated with sexually transmitted disease (e.g., gonorrhoea and chlamydia), and normal fauna of the genito-urinary tract (e.g., Candida) are among those commonly seen in infection of newborns.
  
  Section::::Fetal and placental problems.:Intrauterine bleeding.
  
  There have been rare but known cases of intrauterine bleeding caused by injury inflicted by the fetus with its fingernails or toenails.
  
  Section::::General risk factors.
   "Mycoplasma genitalium" infection is associated with increased risk of preterm birth and miscarriage.
  
  Infections can increase the risk of a miscarriage: rubella (German measles), cytomegalovirus, bacterial vaginosis, HIV, chlamydia, gonorrhoea, syphilis, and malaria.
  
  Section::::Risk factors.:Immune status.
   Vaginal flora in pregnancy
  
  The vaginal flora in pregnancy, or vaginal microbiota in pregnancy, is different from the vaginal flora (the population of microorganisms that resides in the vagina) before sexual maturity, during reproductive years, and after menopause. A description of the vaginal flora of pregnant women who are immunocompromised is not covered in this article. The composition of the vaginal flora significantly differs in pregnancy. Bacteria or viruses that are infectious most often have no symptoms.
  
  Section::::Microbiota in pregnancy.
   There is decrease in immunoglobulin, absolute B-cell counts and total WBC count. T-helper and cytotoxic T-cells are suppressed in proportion of degree of acidemia. These conditions lead to higher infection susceptibility of infant after delivery.
  
  Section::::Pathophysiology.:Fetal effects.:Fetal cardiovascular changes.
   When infected with CMV, most women have no symptoms, but some may have symptoms resembling mononucleosis. Women who develop a mononucleosis-like illness during pregnancy should consult their medical provider.
   Some infections are vertically transmissible, meaning that they can affect the child as well.
  
  Section::::Maternal problems.:Peripartum cardiomyopathy.
  
  Peripartum cardiomyopathy is decrease in heart function which occurs in the last month of pregnancy, or up to six months post-pregnancy. It increases the risk of congestive heart failure, heart arrhythmias, thromboembolism, and cardiac arrest.
  
  Section::::Maternal problems.:Hypothyroidism.
   BULLET::::- PPD 2–3: endometritis ( the most common cause ) risk factors include emergency cesarean section, prolonged membrane rupture, prolonged labor, and multiple vaginal examinations during labor.
  
  BULLET::::- PPD 4–5: wound infection risk factors include emergency cesarean section, prolonged membrane rupture, prolonged labor, and multiple vaginal examination during labor.
  
  BULLET::::- PPD 5–6: septic pelvic thrombophlebitis risk factors include emergency cesarean section, prolonged membrane rupture, prolonged labor, and diffuse difficult vaginal childbirth.
  
  BULLET::::- PPD 7–21: mastitis risk factors include nipple trauma from breastfeeding.
  
  Section::::Diagnosis.
  
  Puerperal fever is diagnosed when:
   Colostral protection lasts up to 5 months of age, after which it decreases to an all-time low to increase yet again at about 12 months of age.
  
  BULLET::::- Prenatal infection: virus travels from infected mother to fetus via the placenta. In this case, the time of gestation determines the result of the infection.
  
  BULLET::::- If the fetus is infected in the first 30 days of fetal life, death and absorption of all, or some of the fetuses may occur. In this case, some immunotolerant healthy piglets may be born.
   Pregnant women are more severely affected by influenza, hepatitis E, herpes simplex and malaria. The evidence is more limited for coccidioidomycosis, measles, smallpox, and varicella. Pregnancy may also increase susceptibility for toxoplasmosis.
  
  During the 2009 H1N1 pandemic, as well as during interpandemic periods, women in the third trimester of pregnancy were at increased risk for severe
  
  disease, such as disease requiring admission to an intensive care unit or resulting in death, as compared with women in an earlier stage of pregnancy.
   These risks appear to be almost exclusively associated with women who previously have not been infected with CMV and who are having their first infection with the virus during pregnancy. There appears to be little risk of CMV-related complications for women who have been infected at least 6 months prior to conception. For this group, which makes up 50% to 80% of the women of child-bearing age, the rate of newborn CMV infection is 1%, and these infants appear to have no significant illness or abnormalities.
  