Pregnancy is accompanied by stress, short sleeps, body pain, frequent urination, multitasking. Physical, and emotionally drained, it is but normal for pregnant women to go through these short memory lapses or to be forgetful.
It is just because of priorities after being pregnant and nothing else:
A 2008 research in Australia found that pregnant women performed memory tasks in the lab as good as non-pregnant women. But, they did not perform similar tasks well back at their home. The researchers in a saying to The Guardian explained a mother's forgetfulness could be due to the change in drastic schedule and life adjustments while pregnant.
The priorities change when you are, a mother in making and your attention too and the memory is as same as it was when you were non-pregnant.
What you can do?
Keep a notepad and a pen with you, set reminders in your cellphone or ask for the help. Get a sound sleep. Don't blame yourself. You are on a great voyage of your life right now.