Reproductive Health

This study, led by Raanan Raz’s team, investigated whether maternal characteristics modify the association between ambient temperature and preterm birth (PTB) in a cohort of over 131,000 births in Southern Israel (2005–2019). Using spatiotemporal temperature estimates and distributed lag Cox models, the researchers found that the association varied significantly by PTB history. Women with a prior PTB showed increased risk with higher temperatures starting early in pregnancy, peaking near term, while no association was observed in women without such history. Although some patterns suggested increased vulnerability among women with autoimmune diseases (heat) and antihistamine use (cold), these interactions were not statistically significant, highlighting prior PTB as the clearest high-risk subgroup.

Raz, et al (2026)

A historical cohort study of 131,599 singleton births in Southern Israel (2005–2019), conducted by Raanan Raz’s team, examined how timing of temperature exposure during pregnancy relates to preterm birth using advanced time-dependent Cox and distributed lag models. The analysis identified late third trimester (weeks 29–37) as the most sensitive window, with higher temperatures associated with increased preterm birth risk, peaking at week 37. A clear seasonal pattern emerged, with pregnancies conceived in autumn showing the highest overall risk compared to those conceived in spring. These findings highlight both critical exposure windows and seasonal vulnerability, emphasizing the importance of timing in assessing environmental impacts on preterm birth.

Raz, et al (2025)

The findings by Shashar et al were recently confirmed by an investigation led by Yaroslav Yousim and Raana Raz (HUJI). Based on the Soroka historical cohort of 129,009 pregnancies, the researchers reported a positive association between temperature and preeclampsia during gestation, especially during 1st and 3rd trimester (Youssim et al, 2023).

We analysed 13 PFAS compounds in placental samples from 50 women who gave birth at Soroka University Medical Center. The study included 10 women with pregnancy complications and 40 matched controls. Five PFAS compounds were most commonly detected, with levels generally similar to those reported internationally. Notably, higher placental PFOA levels were associated with an increased risk of pregnancy-related complications.

A detailed report on the study findings has been published by Groisman et al, 2023.

In the project led by Roni Gat (Gat et al, 2021)we analyzed 84,476 deliveries at Soroka University Medical Center (2003–2013), focusing on preterm birth and preterm prelabor rupture of membranes (PPROM). While preterm birth is widely studied, the authors proposed that PPROM—a spontaneous subset less influenced by medical decisions—may be a more sensitive outcome for examining environmental effects.

Indeed, PPROM showed greater sensitivity to temperature changes than overall preterm birth. Consistent with findings by Shashar et al (Shashar et al, 2020) this effect varied by ethnicity, with Bedouin Arab women showing increased susceptibility to heat exposure in the days before delivery (RR=1.19 per IQR increase).

In another study led by Isabella Karakis (Karakis et al, 2021) , we examined 25 urinary metals in 111 women and their association with their children’s health over the first six years of life. The findings indicated that perinatal exposure to metals was linked to increased risks of pediatric morbidity, particularly asthma, cardiovascular conditions, and obesity.

The team led by Faige Spolter later analyzed 62,547 deliveries between 2004-2013, focusing at late preterm and early-term deliveries as a function of ambient temperature (Spolter et al, 2020). The researchers recorded an increased risk of both outcomes associated with exposure to the highest quintile of temperatures as compared to the central quintile throughout the entire gestation with hazard ratios (HR), 1.31 and 1.24, respectively.

In a study led by Sagi Shashar (Shashar et al, 2020), researchers examined the link between temperature and preeclampsia. Higher temperatures during warm-season pregnancies were associated with increased risk, while similar exposures in colder seasons were linked to reduced risk. These findings suggest that maternal adaptation to temperature changes, and disruptions in heat balance, may play a key role in preeclampsia development.

Important to note, that this was one of the first studies showing differences between Jewish and Bedouin-Arab populations in the Negev, with the latter showing greater vulnerability to environmental exposures. These disparities are largely attributed to socioeconomic conditions, including housing and limited access to climate control.

Our team led by Itai Kloog explored the association between temperature and low birth weight (LBW) and small-to-gestational age (SGA) diagnosis on a population of 56,141 term deliveries taking place in Soroka hospital between 2004-2013 (Kloog et al, 2018). The group found lower temperatures throughout pregnancy being associated with increased risk of both outcomes.

Maayan Yitshak-Sade with other colleagues (Yitshak-Sade et al, 2016) reported a cohort of 1,823 Bedouin-Arab pregnant women recruited at delivery at Soroka Medical Center (2011–April). This analysis included 959 women with verified residence. Exposures comprised temperature, ambient pollutants from nearby monitors (NO₂, SO₂, CO, O₃, PM₂.₅, PM₁₀), and household hazards (e.g., open-fire heating, proximity to waste sites) based on interviews.

Consistent with prior findings, higher third-trimester temperature was inversely associated with birth weight (≈0.002 g decrease per IQR). Among pollutants, only ozone showed an association (≈0.2 g decrease per IQR). Notably, the strongest association with birth weight was observed for self-reported proximity to a waste site, which was linked to a 117.27 g reduction in birth weight.

In a project led by Daniela Landau (Landau et al, 2015), we analyzed 1,024 participants from the previously described cohort, focusing on ambient pollution and congenital malformations. NO₂ showed an independent association with minor malformations, while major malformations were more common among newborns exposed to household hazards.