The difficulty of balancing motherhood and a career can crop up even while you're still pregnant. Depending on your career, you may find yourself excluded from long-term planning discussions as colleagues assume that you won't be around, or won't come back after your maternity leave. Some colleagues may simply treat you differently just because you're pregnant, assuming you can no longer do your job in the same way. You may feel left out of future planning, or feel that your opinions are disregarded since you will not be there to implement them. This can be compounded by the fact that it can be difficult to motivate yourself if you know you won't be there to see a project through to the end.
No one can be certain of being in a job in six months' or a year's time, but you have the advantage of knowing how much longer you're going to work and you may even have a reasonable idea of when you're intending to return to work. Continue to do your job and make it clear by your actions that you want to provide input on all projects, even though you may not be there to see them through to the end. If at this point in time you're intending to return to work after the baby is born, make this clear to any colleagues who may doubt your long-term commitment.
You can also help plan for your maternity leave by, perhaps, dividing up your workload or helping to search for a replacement to cover your role. Being organized now will make the countdown to going on maternity leave much easier in the coming weeks.