I have had constipation for years and have trouble going to the loo if my stools get below 3-4 on the Bristol chart, as I have a diverticule in the bowel, and have had a rectocele repair, so want to avoid damaging it.
It is exaccerbated by slow transit, which is caused by progesterone relaxing the smooth muscle of the intestine. (synthetic progestins do it too). Slow movement through the large intestine means that more water is taken out and stools end up dry and hard.
Tips from a physio with special interest in constipation include: acidophilus capsules, porridge etc (soluble fibre fruit and stuff) for breakfast every morning followed by a hot drink (coffee in particular) and a trip to the loo (using a step, and pelvic floor release - sniff drop flop). The routine will help and you should always go when you feel the 'urge' and not leave it. She also recommended Ortisan cubes which contain some Senna which I did not find helpful as it gave me cramps. She also said to pre-empt known problems with laxitives, eg if I take codeine. Also, plenty veg and water.
TBH, I have tried all of that and it is still an uphill struggle. A hospital dietician friend of a friend swears by kiwi fruit and I found that really did work and is the best thing so far. As well as the fibre, they are supposed to have some enzyme in that helps. The only problem is that now, having eaten them every day for a year, I can't stand them.
Now, I try and follow the physiotherapist's advice, nibble on fruit all day and take movicol as soon as things are not going well, and alternate days during the progestogen part of my hrt.
I hope my experiences will be of help to someone else. I am going to try going without tea as chemenger suggests as I go through loads. It is definitely worth a go.