Can your age predict what birth control you use? A new data set suggests yes.

The type of birth control a woman uses might depend on where she lives — and how old she is.

The health data firm Amino scanned half a million birth control claimsfiled with insurance companies in 2014 and 2015. The researchers focused on women who received long-acting reversible contraceptives (LARC). LARCs are incredibly effective at preventing pregnancy and are becoming more popular; use has tripled in the United States since 2002.

Amino found a few interesting trends in the data. There are two types of LARCS available right now — implants and intrauterine devices (IUDs) — and a stark age divide between who uses which type.

Women in their 30s tend to gravitate toward IUDs, whereas women in their 20s prefer the contraceptive implant.

It’s not totally clear why women gravitate toward different birth control. I’ve heard from doctors I’ve interviewed that younger patients like the idea that they can feel and see the implant — it reassures them that the device is still there and working. Some express worry that an IUD could fall out unnoticed. (Research suggests this is a very rare event.)

The divide might also reflect the fact that getting an IUD is a slightly more invasive procedure, which requires a gynecologist inserting the device into the uterus — whereas the implant is inserted into the arm with a needle that carries the device.

The Amino data also shows geographic disparities in contraceptive preference. In Maine, 11 percent of women using LARCs received skin implants, compared with 47 percent in Texas. On average, the Amino data suggests a quarter of LARC users rely on skin implants.

Again, the drivers here aren’t totally clear. It’s possible that this might reflect local provider preferences; since both devices are similarly effective at preventing pregnancy, doctors might decide to learn to insert just one type. And they might recommend that type to other doctors in the area. Or it might reflect different populations seeking LARCs — if lots of young women are seeking long-acting devices, for example, that could skew a state’s numbers toward the higher end for implants.

Why does this all matter? One reason is it suggests that different women have different preferences when it comes to LARC use. Some women — especially younger women — appear to prefer implants. But public health programs will often focus on just one contraceptive (like a recent effort to get military women better access to IUDs, for example). This data might argue for a more comprehensive approach to LARCs, one that recognizes the different preferences woman have developed.