No, you would need to have stopped fertility treatment/trying for a baby if you are applying to adopt. If a pregnancy happened during the adoption process you would be unable to continue as you would need to focus on the pregnancy and it would be difficult for an adopted child to join a family with a baby. For this reason, you would also be expected to prevent a pregnancy during the process by using contraception, for example.
Whilst we have no hard and fast rules, as some agencies do about how long you need to wait between the end of IVF treatment and pursuing adoption, we would need to be sure that you have emotionally come to terms with the end of that process. Everyone is different and people will process their feelings in a variety of ways. Some people will be ready and able to speak about adoption; others will not yet have got to the point of accepting that they will not be having a birth child. Fertility treatment would need to have stopped before being taken forward to the adoption process.