1.) YakTrax -- These are incredibly helpful to stay steady on your feet during icy Wisconsin Winters. I used them during both of my pregnancies, and loved, loved, loved them! They stretch over your boots to give some added traction.
2.) Layering -- Pregnant people are known for being prone to being a bit warmer than the average, non-pregnant person. Dressing in layers can be helpful for preparing for dressing for the potential extremes of hot and cold.
3.) Bogs -- Bogs are a bit pricy, but they are easy to slip on and off without bending-over. They work as a winter boot (most are comfort rated to -50*F) and a rainboot in one, and are especially helpful to step into when you will have your hands full of your baby and all their supplies.
4.) Moisturizing -- Cold, dry weather can make anyone's skin dry. Your skin during pregnancy might be especially itchy, and in your belly area in particular. A lot of people choose to use balms, lotion bars, and oils to moisturize (I love olive oil and coconut oil, myself!), which you can also use during labor as a massage oil. Keep in mind that moisturizing will not have an effect on wether you will get stretch-marks or not. You can always check with your prenatal care provider to see what they recommend for a moisturizer with more ingredients, too. Using a humidifier and drinking water can also help with dry skin.
5.) Maternity/Babywearing Coat -- I'm all for choosing clothes that work for maternity, nursing, and the postpartum period. Maternity/Babywearing Coats ensure that you will get more out of your coat than just once trimester of pregnancy. Coats that are designed for babywearing and pregnancy can last you for a few years without feeling like you're stuck in maternity clothes longterm.