Tiredness and lethargy can lead to complacency when it comes to brushing and flossing teeth and this is something which must be guarded against.
Hormonal changes and imbalances can increase the likelihood of gum disease which has been linked to premature births and low-weight babies.
Brushing twice and flossing once a day is key to maintaining healthy teeth and gums and there other guidelines that should be followed during pregnancy:
Defer brushing teeth for an hour if suffering from morning sickness as vomit contains corrosive acids
Drink plenty of water and especially when eating snacks or sugary foods
Visit the dentist at least once during pregnancy to ensure all is well
A proper, nutritional, well-balanced diet is essential for the good health of mother and child but, unfortunately, snacking and cravings are undeniable parts of pregnancy -- and indulging in sugary snacks should be kept to an absolute minimum.
Replacing snacks with fresh fruit or sugar-free gum is the best option but not always possible (or desirable) and any sugary snacks should be consumed with plenty of water to nullify their acid content.
More detailed information can be found at https://yourdentalhealthresource.com/how-to-keep-your-smile-healthy-during-your-pregnancy/