THE MEDICAL MIRACLES AND BLESSINGS OF PREGNANCY

In 2002, it was demonstrated that fetal cells may play a critical role in repairing a mother's damaged tissue. In one case, a woman suffering from hepatitis, a serious liver disease, stopped her treatment against medical advice. Surprisingly, she recovered. Her own body could not regenerate healthy liver cells. When a specimen of her liver were tested, it was discovered it incorporated thousands of male cells still left in her circulation from a pregnancy nearly two decades before her illness. Those left over fetal cells had generated new liver cells, and thereby saved the mother's life. "What a nice way for a child to repay its mother's dedication!"

It is a miracle how a mother's body's immune system makes accommadations for having a baby. This is how it works: 

First trimester, the mother's body treats implantation as if it were an open wound that requires a strong inflammatory response. After all, to implant itself in the wall of the uterus, the embryo has to break through the uterine lining, damage the underlying tissue, and distrupt the mother's blood vessels to secure an adequate blood supply. All those activities require an inflammatory response from the mother to secure the adequate repair of the uterus and the removal of dying cells. During this period the mother feels terrible because her entire body is struggling to adapt to the presence of the fetus. YET, WITHOUT HER IMMUNE REACTION, THE PREGNANCY WILL NOT "TAKE".

Second trimester of pregnancy is, in may ways, the best time for the mother. The period is one of growth and development. Both mother and fetuse reach a symbiotic stage that is anti-imflammatory: now that the "wound" is healed, the inflammation had died down. The woman no longer suffers from nausea and fever as she did in the first trimester. 

Third trimester the fetus completes its development. All it's organs become functional and ready to deal with the external world. Now the mother needs to deliver the baby. And delivery, too, is achieved through imflammation: an influx of the mother's immune-system cells into the uterus provokes the release of hormones that induce labor, or contractions of the uterus. The contractions expel, or deliver, the baby. 

The miracle of having a baby is that When a mother conceives a child, that child is a mix of genetic material from both parents. The father's genetic material is foreign to the mother. Normally when the immune system encounters something within the body that is foreign, it attacks and eliminates the outsider, even such needed things as organs or tissues from other people. 

"To appreciate how the ealry fetal cells can cooperate with the immune system of the mother, recall what happens after a sperm fertilizes an egg. The fertilized egg repidly divides to form the blastocyst, a hollow ball of cells with an inner cell mass and outer layer. The inner cell mass gives rise to the embryo, which develops into a fetus about eight weeks after conception, when the major organs of the future baby become recognizable. Teh outer layer of the blastocyst becomes the so-called trophoblast. The trophoblast cells invade teh lining of the uterus and thereby begin implantation. Within a few weeks of making its home in the uterus, the trophoblast further transforms into the fetal part of the placenta, teh conduit for the passage of nutrients and oxygen from mother to fetus. (Some of the mohter's cells form a second part of the mature placenta.)

The immune system eliminates invaders in two ways. The first, known as the innate immune response, neturalizes invading pathogens before they can harm the body. In a wound, for example, white blood cells known as macrophages engulf invading microorganisms and also release signaling proteins called cytokines. The signals activate other parts fo the immune system, such as natural killer cells, which gobble up everything foreign in their path. This response requires no prior exposure to the invader. Acquired immunity is an additional, highly specific, and generally more sophisticated response. It relies on antibodies and specialized white blood cells called B cells and T cells that target particular foreign material to which the body had already been exposed. Those immune-system cells become active and multiply if they encounter molecules or parts of molecules called antigens associated with foreign organisms. The immune-system cells "remember" their encounter with those specific antigens and react to further exposures faster and more vigorously." 

"The trophoblast and the mother's immune system join forces to fight their common enemies: infectious microorganisms. (A mother's immune system to protect her own body from illness is actually heighten because of the immune forces the trophoblast calls to it's aid). When the trophoblast cells "call for help", the mother's immune system responds with coordinated actions. In short, the mother's immune system becomes active in the early stages of her pregnancy to protect, not to harm, the embryo, to promote inplantation and subsequent embryonic growth. 

Think of the cells of the mother's immune system as musicians in an orchestra. The macrophages are one section, the T cells another, the natural killer cells a third. During pregnancy, the trophoblast functions as a guest conductor. The success of the pregnancy- the musical performermance- depends on how well the trophoblast communicates with each kind of cell in the immune system, and how well they all work together. Some responses to the trophoblast signals, are that the natural killer cells help transform the mother's blood vessels, macrophages help the blastocyst migrate to the uterine wall, and dendrictic cells help in attaching the blastocyst. Macrophages also clean up dead maternal cells. When the trophoblast invades the uterus, it sends out signals that program the death of some uterine cells, to make room for the blastocyst. The dead uterine cells need to be removed quickly or disease will result in the mother."

"All the activities of pregnancy can be derailed by viral or bacterial infection. Clinical studies have shown that infections cause as much as 40% of incidence of perterm labor. Furthermore, of the most severe cases of preterm delivery pregnancies that end after less then thirty weeks of gestation), 80% show evidence of infection. 

Inflammation from infection often complicates a pregnancy, jeopardizing the well-being of the mother and her developing embryo. Natures's solution is harsh: to save the mother, the infection not only causes inflammation, but also triggers early delivery, or miscarriage. . . . To our surprise, the signals triggering miscarriage may be initiated by the same quest conductor, the trophoblast. If a virus, say, is infecting the uterus, the trophoblast recognizes the virus through receptors. It's cells signal the mother's immune-system cells to mount an aggressive immune response. Then the mother's T cells and natural killer cells, attack the infection, as well as the trophoblast. The battered embryonic tissue is then expelled; the mother miscarries." 

You need to be careful about bacteria because"too much bacteria can lead to miscarriage," but some may be need because there is a "possibilty that bacteria plays an essential role in priming the uterus for implantation."

Hope you all feel more educated now and see what a blessing and how amazing you can even have a child :) 

From "Pregnancy Reconceived" article by Gil Mor in Natural History magazine 5/07