What are the factors controlling in utero HIV transmission mother to child ? With references.?

Pregnancy Guidelines
The U.S. government has put together guidelines to help HIV+ women make treatment decisions. The guidelines can be summarized as follows:



All HIV+ pregnant women should receive standard clinical and laboratory evaluation. The guidelines also recommend pregnant women take a resistance test if they:

have never taken HIV drugs before
are taking HIV drugs, but have a detectable viral load
To prevent transmission of HIV to the baby, it may be necessary for pregnant women to start or switch HIV drugs; a resistance test will help determine what drugs will work best for you.




For HIV+ Pregnant Women who have not Received Previous HIV Drugs

The standard three-part Retrovir (zidovudine, AZT, ZDV) treatment (described below) is recommended. Women who have a viral load of more than 1,000 copies/mL or whose disease status otherwise requires HIV treatment, should be given the standard three-part Retrovir treatment plus additional HIV drugs according to treatment guidelines for non-pregnant women. Women who are in the first trimester (three months) of pregnancy may consider delaying therapy until after the first 10 鈥?12 weeks of the pregnancy; discuss the risks and benefits of this with your doctor.




The standard three-part Retrovir treatment for prevention of transmission of HIV from pregnant mother to child is:

Retrovir throughout the pregnancy
Retrovir intravenously to mother during labor and delivery
Retrovir syrup given to newborn infant beginning at six to twelve hours after delivery for the first six weeks
All HIV+ pregnant women should be counseled that a combination of HIV drugs (usually three) has been shown to be even more effective than Retrovir alone in preventing transmission of HIV from mother to child.




For HIV+ Women already taking HIV drugs who learn they are Pregnant after the first 12 Weeks of Pregnancy (First Trimester)

HIV drugs should be continued with Retrovir included as part of the drug combination whenever possible.




For HIV+ Women already taking HIV treatment who learn they are Pregnant during the first 12 Weeks of Pregnancy (First Trimester)

Women should talk to their doctor about the benefits and risks of continuing HIV drugs during this time.An HIV+ pregnant woman may decide to stop taking HIV drugs during her pregnancy, if so, all drugs should be stopped at once. Even if a pregnant woman decides not to take HIV drugs during the majority of her pregnancy, Retrovir should be given to the mother during delivery and to the infant after birth to prevent mother-to-child transmission.




Note on Viramune: The guidelines advise against the use of single-dose Viramune in pregnant women who are already taking an effective HIV treatment regimen, since adding Viramune in these cases won't further reduce the risk of a woman passing HIV to her baby and may cause the development of Viramune resistance in the mother.




For HIV+ Women in Labor who has not taken HIV Drugs

A woman in labor who has not taken HIV drugs can still reduce the risk of infecting her baby by using medication during labor and delivery and to treat the baby for a short time after birth. The U.S. guidelines recommend the following options for women in labor who have no history of taking HIV drugs:

Retrovir given intravenously to the mother during labor and Retrovir for the baby for the first six weeks after birth
Combivir (Retrovir plus Epivir) given orally to the mother during labor and six weeks of oral Combivir for the baby
A single dose of Viramune (nevirapine) for the mother at the onset of labor followed by a single dose of Viramune for the baby at 48 hours after birth*
The single-dose Viramune regimen (above) for the mother and infant combined with Retrovir given intravenously to the mother during labor and Retrovir given to the baby for six weeks after birth
*If single-dose Viramune is given to the mother alone or in combination with Retrovir, consideration should be given to giving Combivir (Retrovir plus Epivir) to the mother starting as soon as possible (during or immediately after labor) and continuing for three to seven days; this may reduce the possibility of the mother鈥檚 virus becoming resistant to Viramune. In the period immediately after the birth of the baby, it is recommended that the mother have appropriate laboratory tests to determine whether HIV treatment is recommended for her.




For Babies Born to HIV+ Women who have not taken HIV Drugs Prior to, or During, Labor

The recommended course of treatment is six weeks of Retrovir following birth which should be started in the baby as soon as possible after birth - preferably within six to twelve hours.



Prenatal Tests and Delivery
HIV+ women may want to avoid some of the more invasive prenatal tests, such as amniocentesis, chorionic villus sampling, and percutaneous umbilical blood sampling. Talk to your doctor about whether you need these tests.




There are two types of delivery: Cesarean section (C-section) and vaginal delivery. Elective or planned C-sections are done before labor begins and before the mother鈥檚 "water" (the membranes that surround the baby) breaks. This reduces the baby鈥檚 contact with the mother鈥檚 blood.




Early studies showed that elective C-sections lowered transmission rates. (Emergency C-sections, i.e. those done after the membranes break, do not reduce HIV transmission.)




But today HIV+ women who are on effective HIV therapy and have undetectable viral loads have low transmission rates for vaginal births without C-sections. Since C-sections require surgery, they carry some risks. Women who have C-sections are more likely to get infections than those who give birth vaginally.




For a woman on HIV therapy with a low viral load (less than 1,000), a C-section is not likely to further reduce her already low risk of transmitting HIV. But for a woman with a viral load over 1,000 or one who is not already receiving treatment at the time of delivery, a C-section may reduce the chances of transmission. Speak to your doctor about the pros and cons of each method of delivery.



After the Baby is Born
Since a baby can be infected with HIV through breast milk, it is important not to breast feed if you have other options. You can still have a strong bond with your child even if you bottle feed.




Once the baby is born, he or she will receive three or four HIV tests before getting the final results after several months. During this time, the baby may need to take HIV medication and anti-pneumonia medication. This doesn鈥檛 mean the baby is sick; it is just a precaution to decrease the chances of transmission and illness.



In Conclusion
Deciding to have a baby is a big step for any woman, but for an HIV+ woman, it is even more complicated. Talk to your doctor and OB for "preconception" health care and counseling before you start trying to get pregnant. If you plan ahead, there are many things you can do to protect your health and the health of your new baby.