I did PIH/preeclampsia for one of my presentations - I got a lot of info for it from http://www.preeclampsia.org/
(Preeclampsia Foundation) - really great info for anyone interested...
Two thousand years after eclampsia was described, preeclampsia and eclampsia still complicate 10% of pregnancies yet their cause remains unknown. They are among the major contributors to maternal and perinatal morbidity and mortality worldwide. Preeclampsia/eclampsia is also associated with substantial health problems later in life in both women and their children. While the global financial burden is difficult to calculate, the immediate and long-term annual costs can be estimated as billions of dollars
Global Program to Conquer
2002, World Health Organization
I always found good stuff at emedicine too (these are for preeclampsia but you can find anything there, usually very thorough and up to date):
There are all kinds of things... I'm into breastfeeding so I could come up with a lot there.
Also I think a presentation on the newer forms of birth control could be interesting (NuvaRing, Mirena IUD, patch, Lunelle, Essure, Fertility Awareness, female condom, Yasmin, etc.).
Or breastfeeding and
birth control. LOL
HPV is a big thing lately with the vaccine now out.
Elective c-section & rising c/s rates is another big one.
Here's a list of obstetric topics: http://en.wikipedia.org/wiki/List_of_obstetric_topics