Braxton Hicks are described academically as tightenings which are not uncomfortable and which do not cause a change in the cervix. Williams Obstetrics describes them as “irregular, nonrhythmical, and painless (emphasis mine).”
The above question is the abridged version of your original question. But I’ll quote a portion of your original question, which is a perfect description of Braxton Hicks contractions: “Every once in a while, I will have a tightening in my abdomen that if you touch my abdomen, you can feel it hardening with your hand. Sometimes it is only on one side or just down low, sometimes it is my whole abdomen.”
Generally, Braxton Hicks contractions are seen after 20 weeks, but there can be a little play in this range–so feeling them as early as 19 weeks is quite possible. Since the uterus is muscular, it probably contracts during the entire pregnancy, as soon as the baby grows enough to enlarge it, but these contractions are imperceptible.
False labor, however, is a prelude to true labor, so it is uncomfortable. These contractions usually occur in the last couple of weeks of pregnancy and can be quite painful. But the diagnosis of real labor isn’t made unless there’s a change in the cervix.
- Not rhythmic
- Doesn’t get stronger over time
- Pain usually in lower abdomen
- Can be “sedated away,” using such agents as Seconal, Demerol, Brethine, etc.
- Most important, the cervix doesn’t change
- Regular pattern
- Intervals between contractions get shorter
- Gets stronger over time
- Pain over entire abdomen and even back
- Sedation won’t stop it
- Most important, the cervix changes in dilation, effacement (thinning), and position (moving anterior–in line with birth canal)
The change from Braxton Hicks to false labor to true labor probably represents a continuum, with more and more biochemical stimuli playing a part in the approach to the real thing. Probably the mere mechanical irritation of an expanding pregnancy plays the most part with Braxton Hicks, but the full maternal-fetal-biochemical process stimulates the contraction mechanisms that lead to real labor.