Getting pregnant is a matter of probability. Sperm plays a huge factor in this probability. Your chances of conceiving "naturally" each month are about 15-20% if:

  • The sperm count is higher than 20 million per cc, and
  • There are more than 40 million total sperm, and
  • You are 35 years or under, and
  • Everything else is OK

If he has a low sperm count, your chances of getting pregnant each month are very low, probably less than 5% each month.
With IUI (intrauterine insemination), your chances of getting pregnant with a low sperm count are probably around 10% each month, and with hyperstimulation the conception rate is even higher, probably around 20% or so.
With IVF (in vitro fertilization) and ICSI (Intra Cytoplasmic Sperm Injection) chances of getting pregnant each month are in excess of 40% at most infertility centers.