Smith GC. Use of time to event analysis to estimate the normal duration of human pregnancy. Hum Reprod. 2001 Jul;16(7):1497-500.
BACKGROUND: Current estimates of the average duration of human pregnancy are flawed by inaccurate estimation of the time of conception and by failure to account adequately for the effect of routine elective delivery post-term.
METHODS: In this study, 1514 healthy pregnant women were studied in whom the discrepancy between the menstrual history and first trimester crown-rump length estimated gestational age was within -1 to +1 day difference. The duration of gestation was estimated using time to event analysis: non-elective delivery was taken to be the event, and elective delivery was taken to be censoring.
RESULTS: The median time to non-elective delivery using the Kaplan-Meier product limit estimate was 283 days after last menstrual period (LMP) and there was no difference comparing male and female fetuses. The median was significantly greater for nulliparous women compared with multiparous women (284 versus 282 days, P < 0.0001). Multivariate analysis using Cox's proportional hazards model confirmed the independent effect of nulliparity on duration of pregnancy [hazard ratio, 0.75; 95% confidence interval (CI) 0.67-0.85] and demonstrated no effect of maternal age, previous abortions, fetal sex, high parity, or bleeding before 24 completed weeks of gestation. Bleeding in the third trimester of pregnancy was, however, associated with an earlier onset of spontaneous labour (hazard ratio, 1.38; 95% CI 1.03-1.84).
CONCLUSION: This study provides a basis for predicting the probability of labour at a given gestational age at term.
And so, we wait.
Contractions continue but don’t seem to be going much of anywhere. A woman who works near me but not with me mentioned the other day that she thought I’d have had the baby by now. Ha. Ha ha. Ha. Thanks.
My next appointment is on Tuesday, the official estimated due date (or estimated date of confinement, if you’re into that sort of thing). That will be my last prenatal visit with the midwives. I’ll schedule a non-stress test for the following week and an induction for the week after that. I could refuse, but will I want to, at that point? Induction is more effective with greater parity than I currently have, and there’s nothing to do but wait in order to increase my Bishop score.
Friday, January 27, 2006
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7 comments:
So according to this, your EDD based on a 40 week gestation is actually 4 days short, eh? Sucks.
Hang in there! This will soon be a non-esistent memory (for Emilin, at least). I promise!
Adam tried to refresh my memory of my last weeks pregnant, but I chose not to listen. Thank God for pregnancy/parturition/lactation induced amnesia! I say this assuming that some day I will actually recover my ability to remember things!
Yup. 40 weeks, 4 days is the median (median!). The full text breaks it down into quartiles, and the quartiles split at 278, 284, and 289 days for nulliparous women. Gah.
"Last prenatal appointment with the midwives"? What does that mean? If you go overdue they won't work with you anymore? If you go overdue they don't have you come in, you just wait for Ebry to get a move on? Our midwives will work with us until 42 weeks but you're in there ALL THE TIME from 40-42 ... like every couple days.
Just wondering.
Oh, and not that I'm wishing 42 weeks on you or anything!
At least she got her EDD bumped back two days based on LMP because we know when she ovulated. Using this only puts it back 2 days, but the again, they only included women with 28 day cycles.
The baby will come when it comes. Probably not for another week.
Right. I don't go back to see them until 2 or 6 weeks postpartum (2 if things aren't peachy, 6 if they are). All of my post-date care is done at the perinatal facility.
Ok, kinda baffled now. Who's delivering you? The midwives or someone else? Confuzeled...
Midwives at a hospital.
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