People who are mommied up should note that, especially in the final 3 months, there are some oils you should avoid:
the biggies are
Eucalyptus
Menthol
Pennyroyal
but most of the sinus-clearing, circulation-stimulating are best avoided until you're actually ready to for labor.
At a place i used to work, a mommy came in and wanted to buy some euc/mint foot balm for her fellow to rub her feet with.
Luckily, her midwife was shopping w/ her, and said "OH MY GOD, NO!!" Apparently that's what she, the midwife, would do to help ladies into labor who were overdue and needed a kickstart...