Amniotic levels of nitric oxide and vascular endothelial growth factor in pregnancy with subsequent intrauterine fetal death Andrea L. Tranquilli a,* , Stefano R. Giannubilo a , Valeria Bezzeccheri a , Andrea Ciavattini a , Caterina Scagnoli a , Laura Mazzanti b a Department of Obstetrics and Gynecology, Polytechnic University of Marche, Salesi Hospital, via Corridoni 11, 60123 Ancona, Italy b Department of Biochemistry, Polytechnic University of Marche, Salesi Hospital, via Corridoni 11, 60123 Ancona, Italy Received 6 August 2003; received in revised form 9 October 2003; accepted 28 October 2003 Abstract Objective: Nitric oxide (NO) and vascular endothelial growth factor (VEGF) regulate angiogenesis and seem involved in the early stages of placentation. If angiogenesis is reduced, this may lead to poor placentation and fetal death. This study was aimed to determine whether VEGF and NO are associated to subsequent fetal death. Study design: We retrospectively assessed NO and VEGF on midtrimetster amniotic fluid from seven women who had subsequently had intrauterine fetal death before 20 weeks, and compared the results with those of 14 controls matched for age and gestation. All women had undergone amniocentesis for maternal age. All were at 16 weeks of gestation. None had shown chromosomal abnormalities. Results (mean  S:D:) were tested for statistics with Student’s t-test with significance at P < 0:05. Results: Women with subsequent fetal death had both amniotic NO and VEGF lower than women with normal pregnancy (NO 3:28  1:20 mg/mg creatinine versus 6:02  1:57 mg/mg creatinine, P < 0:05; VEGF 210:10  69:55 pg/ml versus 255:05  88:66 pg/ml). Conclusions: An early reduction of both NO and VEGF may be responsible of an impaired placental vascular development and endothelial regulation that may lead to fetal death. # 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: NO; VEGF; Amniotic fluid; Fetal death 1. Introduction Early pregnancy is characterized by deep morphological changes in the uterine vessels [1], destined to supply the developing placenta. This process is associated with a marked increase in uterine blood flow and a decrease in uteroplacental vascular resistance [2]. The relaxant effect on arteriolar tone is achieved through a complex interaction of many vasoactive substances. It is thought that increased endothelial production of vasodilators, such as endothe- lium derived nitric oxide (NO), during pregnancy is primarily responsible for the observed loss of vascular responsiveness to otherwise potent vasoconstrictors (Figs. 1 and 2). In early pregnancy, the trophoblast invades the inner third of the myometrium as early as 8 weeks of gestation and migrates through the entire length of the spiral arteries; such process completes by the 20th week [3]. In this process, the spiral uterine arteries lose their elastic layer and are trans- formed into markedly dilated uteroplacental arteries. These morphological changes are essential, as they provide for the ever-increasing demand imposed on the maternal placental circulation by the advancing gestation. Genbacev et al. [4] have shown that cytotrophoblast tissues are extremely sensitive to oxygen pressure and that oxygen may be the signal trigging these cells to reduce cell division and to differentiate. When cells from human cyto- trophoblast were cultured under low oxygen tension (hypoxic conditions; 2% oxygen) that mimicked the envir- onment near the uterine surface before the 10th week of gestation, the cells proliferated rapidly and showed little differentiation. When cultured in 20% oxygen, mimicking the conditions around the uterine arterioles, the same cells stopped division and began to differentiate. It appears, therefore, that oxygen tension in the placenta controls the rate of cytotrophoblast proliferation. Once the uteroplacen- tal circulation is established (at about 10 weeks) the oxygen instructs cytotrophoblast cells to stop proliferation and to differentiate into the cells that will form the chorionic villi. As a result, for a proper differentiation, the placenta has to be relatively hypoxic. European Journal of Obstetrics & Gynecology and Reproductive Biology 114 (2004) 162–165 * Corresponding author. Tel.: þ39-07-15962055; fax: þ39-07-136575. E-mail address: tranquilli@univpm.it (A.L. Tranquilli). 0301-2115/$ – see front matter # 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejogrb.2003.10.016