I seem to recall that my post-bacc school had some kind of way for pregnant or otherwise-at-risk women to avoid touching orgo lab chemicals. I think they simply had to put in equivalent hours and demonstrate to the powers-that-be that they had acquired competency in the arcane ways of the organic lab. I doubt that every single school has this kind of accommodation but it’s certainly worth asking and petitioning for, and perhaps you can be a trend setter at your school and help them to create the option where one has not previously existed. It’s probably harder than just doing the lab, but obviously your child’s health (and your own) are much much more important. Best of luck,
Based on what others have said, it sounds like you will have to complete this lab somehow.
There are ways to avoid chemical exposure in a lab environment, sometimes its as easy as just wearing the proper gear and working in a hood.
Most chemistry departments should have a glove box for nasty reactions. With a glove box you are safe and sound from whatever is inside, a bit overkill but its an option to have you complete the same experiments as the rest of your lab class. If your school will not let you use the glove box, plastic glove bags are used for the same purpose just a lot less easy to use. These can be ordered fairly cheap from various lab catalog companies. If you school offers an inorganic lab, most likely they already have some bags on hand.
If none of the above work, ask to have lab experiments assigned that are more baby friendly. You might get the school to buy off on it if you do a little leg work on your own. Find organic reactions that are done in “green” solvents like liquid CO2 or water. If you need to have a distillation experiment (most org labs do) then find one that has less dangerous solvents and can be done in a hood, like water/ethanol mixes. Here’s a link for green chem info
http://darkwing.uoregon.edu/~hutchlab/greenchem/i n…
I feel your pain on this, when I was pregnant I worked as a lab chemist. Consult a toxicologist to be sure if the chemicals in your organic lab are safe for you or not. Nothing against your professor, but a good toxicologist could tell you for sure if that class would be a problem. I gave a toxicologist a list of everything I worked with in the lab and he provided me a list of chemicals that were off limits and ones that were acceptable if I worked in the hood.
Good luck and I hope things work out!! 
Hey here’s the update–yes I have to take it, I spoke to various experts and they think it will be okay while breastfeeding but just in case I am going to try to minimize my exposure by wearing a little mask, being really careful to work under the hood, etc. But it seems like the consensus is that unless I were really getting sick from it, it’s not greatly affecting the milk.
I managed to find a lab that I can do in one month in June. (Fordham University.) Then I can take July off and be ready to start in August.