In the UK it is unlawful to administer any medical treatment without first obtaining valid consent. This principle also applies to expectant mothers and their unborn babies. A mother-to-be cannot be forced to agree to any appointment, examination or treatment, nor to give birth in hospital.
An unborn fetus is not a child in law and therefore the Children Act 1989 does not apply. There is no "best interest of the child" test, nor can any decision by the mother-to-be constitute a safeguarding issue until the child is born.
"If you refuse a treatment, your decision must be respected, even if it is thought that refusing treatment would result in your death or the death of your unborn child."
NHS website
Yes. You do not have to accept any examination or treatment and you can give birth without any help (unassisted or "free" birth) if you really want to. However, any person helping you give birth may commit an offence if they are not a doctor or registered midwife.
It is becoming increasingly popular to have "natural" pregnancies and births with minimal medical intervention, including giving birth at home or other non-hospital setting.
There is no evidence that this poses an increased risk in most pregnancies. As with all medical interventions you should receive relevant information and be allowed to decide without undue pressure. Although you have the right to refuse all medical intervention, this doesn't necessarily mean it is a good idea, especially if your pregnancy does not count as low-risk. Your doctor or midwife will have a duty to inform you of the possible consequences of declining a procedure and you should listen to them. However, if you persist in your
decision, they must not exert undue influence. If you agree to a treatment because you were told that otherwise you will not be seen again at the hospital or practice or that they will inform social services, your consent will not have been freely given and the medical intervention will be unlawful.
Expecting parents need to be aware that the legal situation changes immediately after birth. The newborn now comes under the Children Act 1989 and medical staff need to act in the best interest of the child. This means they are allowed to give emergency life-saving treatment and they may get a court order in advance if they are aware that the parents aren't likely to agree to any treatment which is considered in the child's best interest.