Pushing due to constipation

30 weeks and so constipated today! After trying to go and pushing so much, my belly was kinda achy... Can too much pushing or pushing too hard hurt baby at all or start preterm labor this late in pregnancy? Also, don't really need suggestions for relieving or avoiding constipation (not to be rude), as I already have safe fiber pills, eat yogurt and fruit, and drink PLENTY of water.. just having an off week. Thanks!