Clown fish, a.k.a. ‘Nemo,’ are all born males. If the lone female in the family dies (usually not from old age) one of the males becomes a female, thus guaranteeing the next generation. That’s kind of handy, but certainly not how it works for us.
Our gender is determined at the time of conception through the X and Y genes. Human sperm carries either the X or Y gene and the egg (ovum) always carries an X gene. Millions of sperm are deposited, however only one is generally successful in gaining access to the inner sanctum of the ovum. If that sperm is carrying the X gene, the gender of the developing fetus will be female (XX). If it’s the Y gene, the gender is male (XY). Thus males get to determine the gender of the future human, although in a random manner. But the female takes it from there.
Pregnancy
The term pregnancy simply means ‘pre-birth.’ Of course the actual process is far from simple or safe. We indeed owe a great debt to the female of our species. Imagine strapping a 25- to 35-pound bowling ball (average weight gain in pregnancy) to your abdomen. It must remain there at all times; you can’t unhook your artificial uterus so you can bend over, take a shower, try to sleep, care for children, or work inside or outside of the home. That enlarged uterus also pushes up on the stomach, often squeezing acid into the esophagus producing frequent heart burn; it also compresses the large veins in the pelvis and abdomen causing uncomfortable swelling in the legs and feet that feels like you are walking around on half filled water balloons. The enlarged womb pulls on your back causing it to ache, making it hard to rest at any time.
And that’s the obvious stuff. From the beginning, the fetus is taking all the nutrients it needs to develop, whether or not the mother has a normal nutritional status at the onset of pregnancy or whether she is able to maintain adequate nutrition during the pregnancy. And get this: these ladies are often willing to do this not just once, but repeatedly, thus ensuring success of our species. Unfortunately, this process is not without personal risk of prematurely ending their life in an effort to produce life.
Death risk
Maternal death is defined by the World Health Organization as “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration or the site of the pregnancy, from any cause related to or aggravated by the pregnancy or it management, but not from accidental or incidental causes.” In 2005, the worldwide maternal death count was 536,000. Most (99 percent) occurred in developing (under developed) countries, where one out of every 16 women on average die of pregnancy-related problems, in contrast to one in 2,800 in developed countries. Common causes in developing countries are hemorrhage, hypertension, infection, obstructed labor and unsafe abortion.
In the U.S., the top three causes for maternal death are embolism, hemorrhage and pregnancy induced hypertension (pre-eclampsia). Overall maternal death rates are higher for pregnant black females. And for any pregnant female, risk of intimate partner violence is increased. In at least one state, homicide was the most frequently reported cause of maternal death.
Embolic death
The majority of maternal deaths in the U.S. are due to pulmonary emboli from blood clots and most often occur in the period after delivery (postpartum). Pregnancy causes an increased risk of pulmonary thromboembolus due to an increase in the ability to coagulate blood. The development of hypercoagulation during pregnancy probably takes place to help stop the bleeding that is associated with birth. Unfortunately, this amplified coagulation ability increases the risk of deep venous thrombosis (clot) and thus, pulmonary thromboembolus. Also increasing the risk during pregnancy is venous slowing (stasis) in the legs of pregnant women, which elevates the potential for clot formation and embolus.
Less frequent, but just as deadly, is the amniotic fluid pulmonary embolus. In contrast to a thromboembolus, the amniotic fluid embolus most often occurs during labor and delivery. Conditions that potentially expose the venous circulation in the cervix or uterus to amniotic fluid include: induction of labor, lacerations of the cervix, caesarean section, placental abruption or praevia, and seizures.
Air embolism during pregnancy is rare. Causative factors include sex during pregnancy (especially vigorous intercourse or during oral-vaginal inflation) and instrumentation of the vagina as with a balloon device that is designed to stretch the opening of the vagina (perineum) in preparation for birth.
The increased risk for embolus is present during the pregnancy, during birth, and during the postpartum period. Any pregnant patient that presents with shortness of breath, pleuritic chest pain or hypoxia should immediately bring to your mind the potential for an embolus. Use the information noted above to enhance your history in order to strengthen your suspicions and help direct treatment in the field and facility.
Check back next month for Part 2 of Jim Upchurch’s ‘Maternal Mortality’ series.
References
Wali A, Suresh, MS. Maternal Moridity, Mortality, and Risk Assessment. Anesthesiology Clinics. 2008; 26:197-230
American College of Obstetrics and Gynecologist. Thromobembolism in pregnancy. ACOG Practice Bulletin 19. ACOG 2000; Washington, DC.
Chambliss LR. Intimate Partner Violence and its Implication for Pregnancy. Clinical Obstetrics and Gynecology. 2008; 51:385-397.
Brown HL. Air Embolism During Pregnancy. Obstetrics and Gynecology. 2008; 111: 481-482.
Hoyert DL. Maternal Mortality and Related Concepts. National Center for Health Statistics. Vital Health Statistics 2007: 3(33)