Yes, I know two of my closest friends who both got abortions that now have ovarian cysts... I don't know if its a medical fact but seeing to of my friends suffer from it I'm pretty sure I'm accurate.

Functional Cysts

There are two types of functional cysts - follicle cyst and corpus luteum cyst. Both of these types of cysts develop as part of the natural function of the ovary.

Follicle Cyst. This cyst occurs during ovulation when an egg is released into the fallopian tube or when a developing follicle fails to rupture. These cysts grow from 1½ inches to 2 inches in diameter, and will usually dissolve within one to three months.
Corpus Luteum Cyst. This cyst is caused by a malfunction of the corpus luteum. Unless a woman is pregnant, the corpus luteum disintegrates. But in the formation of a corpus luteum cyst, it fills with fluid and remains in the ovary.

Now to answer your questions: these cysts can often be painful and cause a bit of bleeding. You do need to rest. A corpus luteal cyst is usually not a cause for concern nor does it usually adversely effect the pregnancy or cause miscarriage. I will not lie to you, the cyst itself can rupture, which can cause pain but it should not affect your pregnancy. As far as the progesterone goes: it works two ways. First, it can help shrink the cyst. Secondly, because the corpus luteum produces the hormone progesterone until the placenta kicks in, if you shrink it, it may lose some of its progesterone-producing capabilities. Thus, the progesterone you were given will help there. You were given a transvaginal ultrasound because at 7 weeks, abdominal ultrasounds yield next to nothing on the screen. The cyst can and does cause cramping and light bleeding. It is good that your doc saw that your pregnancy was still intact.

What happens is that when an egg is released from the ovary for fertilization, what remains is the corpus luteum cyst. Basically, it is the remains of the egg that closes back up (into a "cyst") and inside of it is what provides the progesterone and estrogen to the pregnancy until the placenta grows enough to kick in and actually begins to make these hormones on its own around week 7. (they may make you stay on the hormones as long as week 12, though.) Amazing how it all works, isn't it! The loss of this cyst too early is actually a cause for a lot of miscarriages. It is very fortunate to catch it through the amazing ultrasounds these days that see so much and to therefore be able to provide the necessary pregnancy hormones via shots. You getting to the doctor saved your baby! Good thing they knew what they were doing!Some doctors are against progesterone and you probably could have lost your precious munchkin.