Hi Anon 
As far as I know, there r no conclusive studies for the efficacy of nipple stimulation to cause labor. 
Theoretically nipple stimulation if done to simulate suckling by a baby releases the hormone that is similar to the one given to start labor, which give rise to uterine contractions. 
However how much, how often ,this stimulation would cause it or what exactly would be the outcome for mom n baby may depend on other factors, diff from case to case. Eg if the uterus is ready or not etc. 
Labor, delivery, lactation, is all governed by mental, physiological, hormonal etc changes after all.
Whether u can have sex n how to go about it in third trimester, is best answered by ur GYN. 
Tc n all the best.

I am waiting for our expert advice.. &#128522;&#128522;

I also heard bout dis, may be true.... not sure, advice plz @616d5a27c1b4770013bcb718

Dr Shilpitha Singh

Hii.. I have heard that nipple stimulation by your husband in pregnancy in third trimester can lead to preterm labor.. Also the milk related issues.. Is that true? I don't think so in third trimester u can also indulge in sexual intercourse? Kindly guide.. Thanks