Conceptional age, menstrual age, and ultrasound age: a second-trimester comparison of pregnancies of known conception date with pregnancies dated from the last menstrual period.

Ultrasound dating-curve analysis was performed for the biparietal diameter, mean head diameter, and mean trunk diameter in individual singletons, twins, and triplets from in vitro fertilization (IVF) pregnancies and pregnancies with ultrasonographic determination of ovulation. Linear growth was found for all parameters prior to 28 weeks' conceptional age. No differences were observed among singletons, twins, or triplets. Using linear equations, no significant difference was found in systematic errors between pregnancies with a known date of conception and pregnancies dated from the last menstrual period (LMP). Pregnancies with reliable LMPs had only a slight and nonsignificant increase in random errors when compared with pregnancies from IVF. Current polynomial dating equations produced considerable systematic and random errors as well as errors related to fetal growth. Acceptable results were obtained with a new linear equation based on two examinations. We conclude that gestational age based on good menstrual records supported by a pelvic examination in the first trimester may be more reliable than even the best ultrasound method for dating.

A simplified method for determining individual growth curve standards.

To simplify the procedure for obtaining individual growth curve standards, we investigated the use of models derived from the slopes of growth curves determined before 26 weeks' menstrual age. In serial examinations of 33 normal fetuses between 15-38 weeks, we obtained measurements of the biparietal diameter (BPD), head circumference, abdominal circumference, femur diaphysis length, head profile area, abdominal profile area, head cube, and abdominal cube. Rossavik models fitted to these data provided estimates of the coefficients c and s, and fitting linear models to the data before 26 weeks gave estimates of growth curve slopes. Slopes were also estimated from two data points at approximately 16 and 25 weeks. Regression analysis demonstrated a strong linear relationship between loge c and loge SLOPE1 (R2 = 87.3-98.4%), and between s and c (R2 = 64.9-90.3%). Using these relationships, growth models were determined from the slope values. Comparisons between observed measurements and those predicted by these models for the period after 26 weeks indicated that the methods of slope calculation were equally accurate in predicting future growth, and that this accuracy was very similar to that obtained with models based on regression analysis. These results demonstrate that individual growth curve standards for at least eight anatomic parameters during the last 14 weeks of pregnancy can be determined from the data obtained in two examinations before 26 weeks' menstrual age.

Fetal femur length: a critical reevaluation of the relationship to menstrual age.

This investigation has reexamined the measurement of the femur length and the use of this measurement as a growth and dating parameter. Straight-line measurements of shaft length were found to be smaller than measurements made along the bone curvature. However, the maximum difference did not exceed 2 mm. Thus, because of its simplicity, use of straight-line measurements appears justified. The optimal (R2 = 96.1%) growth curve model was a linear-quadratic function, with variability around the regression line increasing with menstrual age. The optimal (R2 = 96.8%) dating curve model was a linear-quadratic function in which loge menstrual age is a function of femur length. The variability associated with age estimates increased with femur length. These data were used to construct new standard curves for growth assessment and dating of fetuses using femur length measurements.

Implications of sino-aortic baroreceptor reflex dysfunction in severe preeclampsia.

Loss of sino-aortic baroreceptor reflex sensitivity has been associated with various forms of hypertension. Baroreflexive dysfunction antedates elevation of blood pressure (BP) in some forms of hypertension, and may play a role in their pathogenesis. We studied baroreflex function in seven women with severe preeclampsia being treated with intravenous hydralazine. As indices of baroreflex sensitivity and hemodynamic competence, we measured the reflexive elevations in heart rate (HR) (delta HR/delta BP) and cardiac index (CI) (delta CI/delta BP) in response to hydralazine-induced falls in blood pressure. The change in cardiac index per unit change in systemic vascular resistance index (SVRI) (delta CI/delta SVRI) served as an additional measure of hemodynamic competence. The results indicated that a higher baseline blood pressure was associated with a dramatic reduction in baroreflex sensitivity (delta HR/delta BP) and baroreflex control of blood pressure (delta CI/delta BP and delta CI/delta SVRI). In patients with higher baseline blood pressures, the severe impairment of baroreflex function eliminated the normal circulatory buffer against vasodilator-induced hypotension. Abrupt and profound reductions in blood pressure and the development of fetal distress in response to hydralazine occurred in the patients with higher initial blood pressures. In addition, the present results suggest that phenomena such as the blood pressure lability and increased responsiveness to angiotensin that characterize preeclampsia are, at least in part, reflections of baroreflex dysfunction.

Mathematic modeling of fetal growth: development of individual growth curve standards.

To provide a more precise means for monitoring individual fetal growth and to improve the detection of growth abnormalities, the Rossavik growth model [P = c(t)k + s(t)] has been used to establish individual growth curve standards. A longitudinal study of the growth of one-dimensional (biparietal diameter, head, and abdominal circumferences), two-dimensional (head and abdominal profile areas), and three-dimensional (head and abdominal volumes) parameters in 18 normal fetuses has revealed that the growth of all parameters can be well-described by the Rossavik model (R2: 97.2 to 99.5%). Strong statistical evidence was obtained indicating that the coefficient k is principally a geometric coefficient having a value determined primarily by the dimension of the parameter being studied. It was also found that the coefficients c and s can be estimated from the data obtained before 28 weeks' conceptual age. Individual growth curve models derived from data obtained before 28 weeks were capable of predicting growth beyond 28 weeks. These models provide growth curve standards for evaluating individual fetal growth beyond 28 weeks.

Variability of ovarian follicular growth in natural menstrual cycles.

Variation of ovarian follicular growth has been found to be too great for conventional statistical methods to provide valuable information when this growth has been related to menstrual age or peak volume day. A method that relates follicular growth to its start (follicular growth age) is presented. With the use of this dating method, variability of follicular growth was found to be within limits that could be handled by simple methods. Follicular volume growth followed a sigmoid-shaped curve and was well described by our growth equation.

Growth curve analyses of follicular growth in the in vitro fertilization program.

A follicular growth model for natural follicular growth was used for a comparison between follicular growth in natural (unstimulated) cycles and cycles in which combination clomiphene citrate/human menopausal gonadotropin was administered for the purpose of in vitro fertilization (IVF). Further, the IVF cycles were subdivided into those cycles in which a spontaneous luteinizing hormone (LH) surge occurred, a pregnancy occurred, or no pregnancy occurred. A comparison of the growth of the dominant follicle between a natural cycle and a stimulated cycle revealed no difference in the appearance of the growth curve. However, follicular growth was initiated 2 days earlier in the stimulated cycles than in the natural cycles. When pregnancy cycles were compared with nonpregnancy cycles, a difference was observed. The cycles in which no pregnancy occurred resembled the growth pattern of the dominant follicle in cycles in which a premature LH surge was noted. These data suggest that follicular growth patterns may be helpful in predicting a favorable outcome before oocyte aspiration and may be a useful adjunct in comparing ovulation stimulation protocols.

Conceptual age and ultrasound measurements of gestational sac and crown-rump length in in vitro fertilization pregnancies.

The growth of the mean gestational sac diameter and the crown-rump length were evaluated from individual series and found to be linear in singletons, twins, and triplets from an in vitro fertilization program as well as in pregnancies with ovulation determined from serial ultrasound folliculograms. No difference in growth rate between the different groups was observed. The 95% confidence limits were 7.7 days before and 7.5 days after mean for the gestational sac diameter, and 5.2 days before and 5.6 days after mean for the crown-rump length. These limits, used together with new linear equations, create less anxiety and less unnecessary surgical intervention than current nonlinear standards when conceptual age is known and the gestational sac or the crown-rump length are too small to be measured.

Ultrasound observations in patients on gonadotrophin therapy.

Twenty-four courses of ovulation induction with HMG-HCG were accompanied by ultrasound sector scanning. The results of cross-sectional studies did not deviate from those reported for normal cycles. Cross-sectional studies indicate smaller peak follicular volumes than repeated measurements of the same follicles. Results may, however, be influenced by frequency and time of measurements, as well as frequency and time of coitus for the patients. Peak-size follicular volumes in patients who became pregnant were relatively large. Peak volumes connected with subsequent pregnancies may therefore have another range of variation than follicles releasing oocytes which will remain unfertilized.

The prenatal determination of fetal weight by dynamic scanning.

An equation based on ultrasound measurements to estimate fetal weight must reflect the relationships between parameters of fetal size and growth as well as the change in fetal shape which occurs in relation to varying nutritional supplies. Four equations have been compared with respect to these demands. The material was collected from everyday practice in our hospital. Good results were obtained using two of the equations, and it was suggested that they may serve as valuable tools in studies of fetal growth.

Comparison of in vitro fertilization results in women with one or two ovaries.

A study compared the in vitro fertilization results in women with one or two ovaries. Eighteen percent (23/125) of in vitro fertilization/embryo transfer cycles were in patients with one ovary. One-ovary patients averaged 4.2 follicles (greater than or equal to 10 mm) as compared to 7.9 in two-ovary patients, and significantly fewer ova were recovered from one-ovary patients (4.0 vs. 5.3). The total follicular volume was significantly less in one-ovary patients as compared to two-ovary patients, and the serum estradiol per follicle was less in one-ovary patients. However, the volume of the dominant follicle, the maximum serum estradiol levels, the number of ampules of Pergonal given and the ovum fertilization rate were not significantly different in one- and two-ovary patients. The mean number of embryos transferred was 3.9 +/- 1.9 in one-ovary patients and 4.5 +/- 1.8 in two-ovary patients (NS). Two pregnancies occurred in one-ovary patients (8.3% per laparoscopy) and 13 in two-ovary patients (12.9% per laparoscopy). The two one-ovary patients who achieved pregnancy behaved more like two-ovary patients in terms of peak serum estradiol levels and number of ova recovered.

Total uterine impulse and cervical resistance at parturition.

Resistance to the passage of the fetus during parturition has been estimated indirectly by calculation of the active contraction area during the first stage of labor until the cervix reaches a dilatation of 5 cm--the period of cervical resistance. Parturients with a high total uterine impulse in this period were studied. Two different patterns of cervical resistance with corresponding clinical pictures were found. Type I had a high frequency of cesarean sections with a good correlation to the resistance. With high resistance there also was a tendency to low Apgar scores at 1 minute. Type II had normal 1 minute Apgar scores and only vaginal deliveries.

The predictive value of cardiotocography.

Continuous fetal heart rate (FHR) recordings from 200 parturients in first stage of labour were evaluated according to conventional systems and compared with the Apgar scores at one minute. The results were disappointing, but they indicate that an improvement could be achieved by taking into consideration the periodical total uterine impulse (TUI) in the first stage of labour.