I had terrible problems with systemic candida yeast overgrowth after giving birth to my 2 kids. (The problem stemmed from being given lots of antibiotics as a child, but it came to a head during pregnancy.) It resulted in many symptoms, including depression, irritability, brain fog, fatigue - and low sex drive. Like, zero for a while.
You can google Candida and find lots of good info. This is an EXTREMELY common ailment. Lots of people suffer from it but chalk it up to other things. Pregnancy makes it worse, because of the hormones.
It took me over ten years of trial and error with radical diets and many different kinds of supplements, but I'm beating it. If you think this might be an issue for you, here's what I would suggest (this should save you years and a boatload of money vs. trying to take potshots in the dark on your own:)
First, find a qualified practitioner. This probably won't be an MD. Find someone who can give you a blood test that they send out to a lab and tells you EXACTLY what nutrients your body is lacking. (Probably you'll need lots of natural Vitamin B complex, but they'll be able to put you onto the right one.) If it's a competent practitioner they should be able to give you the dietary information you'll need to cope, as well as set you up with a high-quality probiotic. (No, just eating yogurt isn't enough if your candida is severe enough to destroy your libido.)
After about 8 years of struggling on my own and seeing various practitioners who did minimal good, I finally found Barbara Bradley in Wausau, WI. Her nutritional analysis and treatment made a huge difference in my overall well-being.
But it wasn't until I tried ThreeLac that I got my libido back - and I mean RAGING back. You can order it online. You'll want to do some background reading, though. There are some slightly scary claims about it, so you'll need to decide if you want to try it. (If you do, I'd suggest working on your general health first.) But for me it is the one thing that is finally bringing me back to full health. (I don't sell the stuff - this is just my experience.)
If you think Candida may be an issue, hang in there. It's difficult to beat and can take years (you didn't get to this stage overnight) but it can be treated successfully!