Prolifers will always try to attack abortion rights that's what they do. So I do feel scared at the prospect of a DUP coalition.
Nadine Dorries tried (and failed) to reduce the abortion time limit under a Labour govt (the very same Labour govt who did not extend abortion rights to NI when they had a massive majority.. ). I thought after that, that getting that hearing and having their day in parliament really emboldened the anti choice brigade and multiple other shitty attempts followed after that led on by Daily Mail and the Torygraph. Like around sex selection and sexism-or disability rights- and restricting abortion.
And probably no coincidence that pro life picketing of clinics and political lobbying really stepped up a gear after that.
I do think having enough prolifers in elected office and with actual new political power because the Tories need them, could give the anti choicers the ability to shift the window in the public debate because they will get an unprecedented media platform and they will hold all the horse trading cards with the Tories.
Cameron was an utter utter bellend (understatement) but in his haste to be seen as socially liberal 
he did not want to touch abortion. In fact and he and Osborne were publicly dismissive to Dorries via 'Calm down Dear' which has basically kicked her and her ilk into the long grass.
But now.. If there is a coalition with DUP/Tory the Tories will not be able to afford to challenge the prolifers in the mix on some of their most closely held ambitions.
The antichoicers play a long game because they think they have God on their side, they are not scared of repeated defeats in Parliament but relish the repeated airtime.
They know they will fail by draconian calls to ban all abortion etc or by appealing to religious voters only, but.. by chipping away at the edges over a long time they hope to shift the window of what is publicly acceptable and so get closer to dismantling legal NHS funded abortion access.