Interpretation
The results of this study are in line with most relevant scientific
findings on this subject. We previously demonstrated a greater incidence
of complications in women with values of SVR higher than 1069 d.s.cm-5
in the early stage of labor10. Kalafat e al.
demonstrated that higher SVR correlates with an increased risk of
operative delivery due to presumed fetal compromise in women undergoing
induction of labor for several indications11Kalafat E, Barratt
I, Nawaz A, Thilaganathan B, Khalil A. Maternal cardiovascular
function and risk of intrapartum fetal compromise in women undergoing
induction of labor: a pilot study. Ultrasound Obstet Gynecol. 2019 Nov
11.. Even in our study the SVR value is the best independent risk
predictor for delivery complications and shows a strong association when
is higher than 1135 d.s.cm-5 (OR = 9.01).
In our study, women who developed complications during the labor, showed
increased SVR, reduced CO and higher PKR. The FTc, which represents the
time of the left ventricular systole and is correlated to preload and
cardiac performance, is apparently an independent predictor of
complications on multivariate analysis when is higher than 365 ms. This
hemodynamic pattern, characterized by a high resistance and hypodynamic
circulation, is characteristic of a cardiovascular maladaptation and
this condition is significantly correlated with the development of fetal
sufferance during the labor.
We can only hypothesize which is the etiopathological mechanism that
determines the development of complications during the labor in patients
with suboptimal cardiovascular status even before labor starts. The
cardiovascular adaptation to the pregnancy is fundamental for adequate
perfusion of the uteroplacental unit during the pregnancy and prevent
placental syndromes22Valensise H, Novelli GP, Farsetti D,
Vasapollo B. Cardiac function. In: Lees C, Gyselaers W, editors.
Maternal hemodynamics. Cambridge (UK): Cambridge University Press;
2018.
In normal pregnancies the vascular remodelling leads to a SVR reduction
and a CO increment that are fundamental for a correct uterine perfusion
and to prevent fetal hypoxia. During the labor there is an increase in
demands on the cardiovascular system, in particular CO increases by 30%
in the first stage of labor and by over 50% in the second
stage21. Women with high SVR and poor cardiac
performance at term have not fit properly to the pregnancy and have an
increased risk to develop intrapartum complications. The poor cardiac
performance could be the cause of a reduced uteroplacental perfusion and
a consequence fetal sufferance. The subclinical alterations in cardiac
function, in apparently healthy women, could compromise the delivery
outcome.
Even in our results, the multiparity is a protective factor for the
development of maternal and fetal adverse outcome. The OR value is
superimposable to the OR calculated by Kalafat et
al20. The maternal hemodynamic parameters, adjusted
for multiparity and maternal height, showed to be independent risk
factors for adverse outcome.
The CPR has been demonstrated to be able to identify fetal at risk for
distress during labor, even in AGA fetuses3322DeVore
GR. The importance of the cerebroplacental ratio in the evaluation of
fetal well-being in SGA and AGA fetuses. Am J Obstet Gynecol 2015;
213: 5–15. Nevertheless, in our results the CPR value, adjusted for
the gestational age, didn’t show significant difference in patients who
will develop complications.