I think Lactulose is very effective but maybe more so on some- for me one dose is enough to have everything coming out! Although I think I would be cautious with it towards end of pregnancy. I was due the 18th December and nothing had happened, no sign of baby, wasn't even sure she had dropped. Was so uncomfortable from constipation that decided to take Lactulose for first time in the pregnancy. Woke up at 5am and literally cleared everything out (tmi but it was not pretty!) but I still felt a bit sore and wasn't sure it was finished so I went to lay on the sofa at 5.30 rather than wake my partner up being restless. 6.05am I'm on the sofa and feel this massive pop (almost like a huge kick) and that was my waters gone and I was in labour! Don't know if they are related or not but I feel like maybe the pressure of getting the poop out got things moving! X