1-Parental chromosome abnormalities causing Recurrent Miscarriage ( Abortion ):
identified in between 3-5% of couples with Recurrent Miscarriage. The most common cause is balanced or reciprocal translocation twice as many females compared with males are identified as carrying structural chromosome abnormality, this is most likely due to structural abnormalities with males associated with infertility.
Trisomy or Monosomy is the most common identified chromosome abnormality in human miscarriage; about 30% of miscarriages are trisomic and increase with maternal age.
3- Endocrinopathy causing Recurrent Miscarriage ( Abortion ): -
Luteal phase defect which have women with recurrent miscarriage, the diagnoses of luteal phase defect based on luteal phase progesterone level and endometrial biopsy patient with PCOS associated with higher rate of pregnancy loss. Hormonal responses of the endometrial to be receptive to the embryo.
4- Antiphosphlipid syndrome:-
it’s the most important treatable cause of recurrent miscarriage. In the first trimester of the pregnancy, the majority of miscarriages accrue, after fetal heart which ascribed to thrombosis of the uteroplacental vasculature using of Aspirin alone as prophylactic agent increase live birth to 40% , when adding heparin with aspirin the rate will increase to 60%.
6- Immune dysfunction which causes of Recurrent Miscarriage ( Abortion ):-
a. (NK) Natural killer cells: The Lymphocytes, part of immune system present in peripheral blood, have more killing ability than uterine natural killing (NK) cells.
b. Embryo has to be receptive to implantation. This needs continuous interaction between embryo and uterus mainly by cytokines which secreted by the immune cells of the uterus. If immune cells don’t respond to the signal from embryo adhesion and implantation will not occur.
7- Structural uterine abnormalities causes of Recurrent Miscarriage ( Abortion ): -
The prevalence of uterine abnormalities among women with Recurrent Miscarriage range from (1.8-37.6) %
8- Uterine environment that inhibits embryos from implantation, classified as anatomic, hormonal and immunological:
i. Endometrial polyps: Benign outgrowths of the endometrium in the uterine cavity.
ii. Sub mucous fibroids: Benign tumors which protrude from the uterine wall into the uterine cavity.
iii. Uterine Synechia: Due to scarring or adhesion in the uterine cavity.
9- Infectious agents causing Recurrent Miscarriage ( Abortion )
10- Environmental: - tobacco, alcohol, radiation chemotherapy
11- Psychological causes of Recurrent Miscarriage ( Abortion ).
12- Idiopathic (Unknown): - 40% of recurrent pregnancy loss