Does antibiotic affects conception?

No.: There is no effect on ovulation / fertilization or implantation. There are some antibiotics that clearly should be avoided in early pregnancy. In fact it is a good idea to avoid antibiotics unless you really need them.

Probably not: What information there is for each antibiotic is contained in the product labeling for the drug under the category special populations, pregnancy. Studies on this issue have generally not been performed. While there is a chance for antibiotics to change the envirnoment of the vagina and uterus to render them less hospitable for sperm, the lack of reports & studies would suggest a low likelihood.