Do you use a HRM, Breda? If so, aim to keep your heart rate under 150bpm and you're unlikely to run into too many problems. Pregnancy changes your exercise tolerance, so you may find you're barely doing more than brisk walking at that level. Racing is unlikely to be a realistic proposition.
Ordinary running gear is accommodating enough for a small-to-middling bump, and by the time your bump is big you may be too uncomfortable even to run for the bus.
There are a couple of well-documented instances of elite athletes running until well into pregnancy (Ingrid Kristianson, Liz McColgan, our own Monique), but not everyone can. The first three months of pregnancy can be so exhausting that the very idea of running would make you laugh if only you had the energy and could open your mouth without heaving.
I think Emma Litterick's "listen to your body" advice is as good as it gets, and I hope she listens when her body tells her it's time to STOP running.