( Andrea added more information, Thank you! )
It is really important to go to a clinic as soon as you think you might be pregnant. Right when you miss your first period. If you want to give birth in Tsukuba, choose a clinic that can also accept you for the birth. Many clinics deal with the pregnancy itself, but you need to find a different hospital for the big event!
Right now in Tsukuba (December 2007) there are only four places in Tsukuba that allow for deliveries:
Shoji Maternity Clinic
Nanairo Maternity Clinic
University Hospital (you will need an introduction from a regular clinic before you can go to the uni hospital)
In Japan there is a shortage of hospitals/clinics for deliveries. If you don't reserve a bed for your birth early, the chances are very high that you will have to travel out of Tsukuba.
If you are just thinking about starting a family, I recommend to visit a few clinics to see what you think, then you know where to go later. Also, it means you will have a patient card for each hospital, so in an emergency it is easier for them to accept you.
Lastly, please be aware that the style is a little different to Western countries. In Japan you sit in a special chair with footrests. The nurses will put a curtain across between you and the doctor, but if you don't like it you can tell them 'No curtain, please' :) Also understand that you will almost always have an internal ultrasound test for any kind of checkup. For early pregnancy, you will get the internal ultrasound every time, and it will switch to an external ultrasound when the baby gets much bigger. If you DON'T want to know the sex of your baby, please tell the doctor and nurses at first. Nowadays the pictures are so clear, you can very easily see.
Thank you so much, Andrea! I think you know the clinics better than Japanese people.I got a lot of new information from you and international women's network friends. Thanks a lot! Kumi