I can't vouch for the efficacy of essential oils used during labor, but I can't see that it would cause any harm (so long as the oils are chosen carefully and diluted).

While Lavender is always a good choice for calming, there are other essential oils which can be used individually or in concert. Palmarosa, Geranium, Roman Chamomile, Rose, Rosewood, YlangYlang, Bergamot, Jasmine, and even Lemon can be diffused or dabbed on a handkerchief or pillow case.

The following "recipe" might also help after labor begins:
4 drops helichrysum
4 drops fennel
2 drops peppermint
5 drops ylangylang
3 drops clary sage

Mix all the above in 1 ounce of carrier oil (refined coconut oil, sweet almond oil, olive oil, refined avocado oil, sesame seed oil, grapeseed oil, wheatgerm oil, sunflower seed oil, or any combination of these).

After labor starts, apply to reflexology points on hands and feet which correspond to reproductive area. Also rub on lower stomach and lower back.

Disclaimer:
Please note that the information presented in this post is not a substitute for professional medical advice. Please contact your doctor before using the information presented here.

Personally, I couldn't smell anything without wanting to smash it. My husbands parents came in with Arbies... ick... and all I could smell was the onion.. I LOVE the smell of onion, I did not love it while I was in labor.

I think you may be better off skipping aromatherapy, but who knows not everyone will react the way I did.

If you did opt for it I would go with smells that personally comfort you. Who cares what other people think. For example, say you grew up near an orchid and the smell of apple blossoms ties strongly to the comforts of your youth.. try apple blossom.

After a century of highly medicalized prenatal care and childbirth, the trend in recent decades has swung back toward natural, gentle birthing techniques. Midwives and doulas, once frowned upon by the medical establishment, are now being welcomed into hospitals, oftentimes replacing doctors at the pregnant woman’s bedside. Much has been written about the benefits of water, hypnotism, and naturopathy in prenatal care and childbirth. This article will focus on the use of aromatherapy to ease the discomforts, relieve emotional stress, and maintain good health of mother and baby throughout pregnancy.

http://www.aromatherapy-blends.net/aromatherapy-in-pregnancy.htm