If timing goes wrong, we will have trouble. Imagine the cervix does not ripen on time but you’ve got active contractions, so you’ve got a babies head pushing on a closed cervix. This is very dangerous for the baby, it can cause fetal distress. Sometimes the cervix ripens too soon (can happen as early as 22 weeks). So we need things to happen at the right time and right order.
Ferguson reflex, this is a classic neuro-endocrine feedback loop. As the foetus enters the canal you get sensory neurones in the cervix feeding back to a part of the brain to stimulate oxytocinergic neurones to stimulate release of oxytocin. This goes round to the uterus and stimulates forceful contractions, and this carries on until that baby stops distending the cervix. Oxytocin stimulates the final push and we can get the acceleration.
If you measure progesterone in mice, it goes up until day 17 and then drops off a cliff, that is when the corpus luteum is involuted. This is not the case for humans. Oxytocin is not essential for normal delivery in mice, they worked this out by producing oxytocin knocked out mice. However, the mice died from not having the milk let down reflex, so oxytocin is critical for ejecting milk.
If you have just saline, after about 3 1/2 days from the start of the treatment, both will deliver. If you give the oxytocin to quite a low amount, the mice will have a delay of one day. Increase it further, and the knockout is delivering preterm and within 1 day of the treatment, wild type still has extended day, if you increase further, both go into labour immediately. A clear discrimination between dosing.
A little history of IVF
The first human fertilisation in vitro took place in 1969. They began unsuccessful. The First IVF pregnancy in 1973 led to early miscarriage; and in 1975 was an ectopic pregnancy. And so it caused ‘harm’ and led to the question ‘should it have taken place?’
In 1978, the first IVF baby was born, Louise Joy Brown, who is still alive today with her own kids. There have now been more than 8 million IVF babies born worldwide. So a lot has changed in the last 50 years.
Who should receive state-funded NHS IVF?
This is decided following clinical ‘evidence-based’ guidelines from NICE (the National Institute of Healthcare and Excellence.) People can be assessed for whether they have fertility problems, and treatment can be given for those people. Access to IVF varies depending on where you live, hence the term ‘postcode lottery,’ as some areas provide greater access. The NICE recommendations give 3 cycles for women aged 23-29 with a defined cause of infertility or 3 years with unexplained infertility. One cycle may be given to those older, but younger than 43.