No, no harder for queer women in general than any other group of women. It comes down to the individual. I'm guessing the question comes from the assumption or experience that lesbian women don't have intercourse?
Just to provide a PSA from a local sex-loving lesbo to all those who might not know this: queer women have some pretty crazy sex, in my experience. In my experience, lesbian sex includes toys of all kinds, including dildos of various shapes and sizes and various activities including everything from a few fingers to double-handed fisting. Back to assumptions, lots of straight women don't do much more by way of intercourse besides their primary male partner's penis, which in no way mimics an infant's head.
I think perineal massage is every pregnant woman's best friend and is a great way to get the stretch going. I think women who have some experience with stretching (toys, fists, penises, previous labour) will have an 'easier' time than women who've not had much penetrating action down in their nether bits, straight or queer.
There are so many variables; body shape, baby size, baby position, length of labour, fatigue, hunger, psychological state, support and preparation for labour, labour position, medicated or not medicated, etc.