J.S.
Hi M..
I got pregnant when my still nursing son was 16 mos. I nursed him through the pregnancy, but had to night wean him when he was around 18 mos because I just couldn't get enough sleep and was a total zombie. I kept nursing him during the day, but did cut him down to just a few sessions a day. As my milk supply got lower, he wanted to nurse more often and for longer periods of time. I stayed hydrated and ate well, but pretty much lost my milk at around 5 mos pregnant. This did not deter my son, who still wanted to nurse constantly. Unfortunately, my nipples became so sensitive that it was very painful for him to nurse. I ended up cutting him down to one nursing session/day (in the morning) for the 7th and 8th month of my pregnancy and then tried to wean him before the baby came. That was not my original plan -- I had wanted to nurse through the pregnancy and tandem nurse afterward.
So, now my new baby is 8 weeks old, my son is 27 mos old and I'm trying to tandem nurse. My son didn't take to weaning -- everything I read said the child will eventually stop asking to nurse. My son didn't. He asked me several times a day every day. And then he started asking any large breasted woman he saw which lead to some embarrassing moments at restaurants or in the grocery store. It also broke my heart, since I had intended to keep nursing and felt bad for trying to wean. After my 2nd baby was born and my milk came back in (and waaaay more milk than I ever had the first time) I started letting my toddler nurse again. Now I'm just trying to balance the 2 of them because my son still wants to marathon nurse -- he won't let go until I make him and then throws a tantrum. He will nurse for over an hour and still want more. Some days my breasts are pretty much in constant use!
Good luck! I hope everything works out for you the way you want. Oh -- I forgot to say -- my Dr. recommended that I wean by 20 wks because nipple stimulation causes contractions for some people (she actually said "It is recommended that you wean by 20 weeks, but do what you feel comfortable doing"). The nursing did cause me to have some strong braxton hicks type contractions in the 3rd trimester, but nothing that felt like "real" contractions.