Pregnancy Loss in the First Trimester
Vol.1 No.1   

This month I begin a series of discussions about pregnancy loss (miscarriage, fetal demise and stillbirth.) I have attemped to write this and subsequent reviews in a manner similar to that which I would use to speak with my patients. I invite all users to ask questions anddiscuss experiences through the private E-Mail area and the Grieving and Sharing Registry.   

As extraordinary as it might sound, at least 15% of clinically recognizeable pregnancies end in fetal loss. We can separate losses into several different categories but for clarity I will classify them temporally throughout the pregnancy as:  

1. First trimester-conception through 13 weeks.  
2. Second trimester-14 weeks through 26 weeks.  
3. Third Trimester-27 weeks through 40 weeks(term.)  

This month Hygeia will review first trimester losses.  

The most frequent losses occur in the first trimester either as spontaneous abortions(miscarriages) or Ectopic Pregnancies. Up to 50 per cent of all tissue from miscarriages demonstrate chromosomal abnormalities. Therefore, chromosomal abnormalities are the primary cause of miscarriages. These aberrations occur early in embryonic development and many times do not even manifest a fetus. Unless one or both parents are carrying an abnormal chromosome, the risks of recurrence for these early miscarriages is low.  

Implantation (the establishment of a maternal/fetal unit) can be interrupted by a deficiency or imbalance in the production of maternal hormones, most often progesterone from the ovary and thyroxin from the thyroid gland. Maternal bacterial, viral or viral-like infections have also been associated with first trimester pregnancy losses. Three in particular are mycoplasma, chlamydia, and gonorrhea.  

Mycoplasma can actually be a cause of recurrent spontaneous abortions while chlamydia and gonorrhea can also infect the uterus and fallopian tubes and damage the very delicate lining of the tubes(called tubal endothelium) and create a hostile environment for the transport of the fertilized egg promoting an increased risk for a tubal or ectopic pregnancy.  

Other factors which have been implicated as causes of first trimester losses include auto immune disorders such as the Anti-phospholipid syndromes, substance abuse, cigarette smoking, multiple pregnancies and placental abnormalities such as gestational trophoblastic diseases, the most common being molar pregnancies.  

Treatments for imminent miscarriage or first trimester loss are unfortunately usually expectant. Attempts have been made to prescribe strict bed rest, administer hormonal supplements as well as other exogenous therapies. In circumstances where there is a viable pregnancy and significant vaginal bleeding, bed rest might be beneficial to reduce trauma in an already precarious pregnancy. Such is the case with the so called vanishing twin syndrome where conception resulted in a twin gestation but one twin aborts causing bleeding while the remaining twin is viable. Progesterone therapy is thought to be of value in circumstances where it is felt there might be a reduction in progesterone production from the ovary leading to poor embryonic development(inadequate luteal phase.) Aspirin, steroids such as prednisone and heparin have been used with some success in the treatment of immunological causes of pregnancy loss. Next month, the review continues with second trimester losses.  
  
 

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