I may sound ignorant.... but was wondering is it a must to sterilize baby's feeding bottles?

I would suggest to best continue sterilising your baby’s bottles until he/she turn at least a year old. Babies are vulnerable to the germs that cause diarrhoea and vomiting. These germs can develop very easily in milk. Bottles and teats have nooks and crannies that milk can collect in. Sterilising is the only way to ensure your baby's bottles are free from harmful bacteria. By the time your baby is one year old he/she will have started to produce his own antibodies and be more resistant to harmful germs. Hope it helps.

During the first year of your baby’s life, he’s at his most vulnerable to illnesses. If bottles aren't sterilised, viruses, bacteria, and parasites can gather and make your baby ill. Your baby could develop anything from mild thrush to a more serious bout of vomiting and diarrhoea. It's not possible or practical to create a totally germ-free environment for your baby. But by sterilising your baby’s feeding equipment, you can help to keep him healthy.

Typically, hot water, soap and some scrubbing is sufficient to help clean the bottles. If you have a sterilizer, it is quite convenient and most of my friends use those after each feed. Doctors usually recommended that the most important time to sterilizer a bottle is when it is newly bought, before the first use.

You can stop sterilising gradually after baby starts solids. If baby have not started solids, it will be good to at least sterilise the bottles once per day and rinse with hot water thereafter.