Can sperm count drastically change?

4 years ago my husband and I did IVF with ICSI due to my husbands low sperm count and low morphology.

Last week we went back to a fertility specialist and did a new semen analysis. We got the results back and everything is completely normal and he is completely fertile? Does that happen often? I feel like we were told his sperm count and morphology would always be low?

We have a follow up with our doctor so I’ll ask her this too but with his sperm analysis coming back normal is it a little less likely we’ll have to do IVF again?

Additional info …

- we did conceive our second child after one month on femara

-we’ve currently been trying since November 2020

-I have pcos and and my TSH just came back slightly elevated so from here on out I will be taking thyroid meds and femara

Thank you!!!