Definition - What does Implantation Dip mean?
An implantation dip is a one-day drop in basal body temperature (BBT) during the luteal phase of the menstrual cycle, occurring around 7 to 10 days after ovulation. An implantation dip is seen more often in women who are pregnant than those who are not. An implantation dip may be used as additional evidence in positively predicting pregnancy, however, without additional signs and symptoms of pregnancy, the implantation dip alone is unreliable.
FertilitySmarts explains Implantation Dip
After ovulation, during the luteal phase of the menstrual cycle, progesterone surges and causes the BBT to elevate slightly for the duration of this phase in the menstural cycle. An implantation dip is a one-day drop in BBT occurring around 7 to 10 days after ovulation. A BBT decrease at this time normally indicates the end of the luteal phase and the initiation of a period. However, in the case of the implantation dip, the decrease in BBT only lasts for one day and immediately increases again. Progesterone, which is the chief hormone in pregnancy, causes a sustained increase in BBT and may be responsible for the immediate rebound in increasing BBT. Because implantation of the embryo usually occurs between days 7 and 11 of the luteal phase some people have association this one-day BBT decrease to implantation.
Although an implantation dip does occur more frequently in women who are pregnant, it also occurs on occasion in non-pregnant women and is not a reliable sign of pregnancy. Additional signs and symptoms or better yet, a positive pregnancy test, are necessary to definitively determine pregnancy.