Okay, first of all, relax. The Tower is not a "negative" card. In fact, it's one of my favorite cards of the deck!
All it means is that a sudden, sometimes chaotic change is coming. Now, sometimes change isn't pleasant, but it's necessary for growth. Someone told me something once, many years ago, that stuck.
Think of a forest fire. It's chaotic, destructive, and deadly. However, without forest fires, the forest would very quickly die. Fires replenish the soil and make way for new and stronger life.
I've always seen the Tower in this way. True, there may be a chaotic, destructive period of your life, but it will only be temporary (sometimes it's a matter of a few hours!) and on the other side of that period, you will be stronger, smarter, more wise, and overall a better person for the experience. And keep in mind that it doesn't ALWAYS have to be destructive. Just as a forest fire is necessary for the health of the forest, the Tower is necessary for your health and growth as a person. It's a beautiful, wonderful thing! It means that you're growing. That you're constantly evolving, and that you care enough about yourself as a person to continue your personal growth.
Oh, and by the way... Giving birth to a child can DEFINITELY be described as a sudden, chaotic change. I'm speaking from experience, here. Being pregnant and mentally preparing yourself means nothing once the baby is born. For me, it was my first child, and it was absolutely the most chaotic time of my life. Nothing could have prepared me for that.
Chaotic? Yes. A sudden, abrupt change? Hell, yes. The Tower came up quite often for me in the months during my pregnancy, and even that wasn't enough to prepare me for motherhood. But it was unbelievably POSITIVE!
And that's just one example of what the Tower could mean, especially with you being pregnant. So perhaps that's what the Tower is telling you, as well. Something chaotic and crazy is coming, but it's a beautiful thing. Embrace the change. Embrace the chaos. Love every moment of it, even when you're scared out of your wits. Pregnancy is a chaotic, hormonal, emotional, time. Cherish that precious, chaotic, crazy time. THAT'S what the card is telling you to do.