Hi, Thanks for consulting us. Oligohydramnios & non-visualization of kidneys may indicate presence of a genetic or congenital abnormality which is not avoidable. Nothing can be said about the cause of your first miscarriage, although approximately 50% of pregnancies that result in miscarriage during first trimester are genetically abnormal. This speculation can be confirmed if the fetus or products of conception are studied in lab ( genetic testing or karyotyping). This can also give you some idea about the potential of recurrence. If this test was not done before, you (both partners) should also have karyotyping. If in fact genetic abnormality turned out to be the definite cause, you can t do much about it ( apart from options of gamete / egg donations or adoptions. Otherwise, if no genetic cause then low dose Aspirin & LMWH ( low molecular weight heparin) may do miracles in future pregnancies. Better is to consult a good Gynecologist for full investigation & future help. Wish you good luck. Regards.