Life imprisonment doesn't mean she'll be serve life. She may be given a minimum tariff of only a few years. This was murder, not manslaughter - that might have been an error on the part of her defence team or perhaps she refused to plead to manslaughter.
Unfortunately she was contacted repeatedly by multiple services during her pregnancy and she didn't engage at all which doesn't help her case.
Dumping a newborn baby in the woods was not her only option.