Pregnancy Outcomes After Parental Cell Phone Exposure: Norwegian Mother/Child Prospective Study

Pregnancy Outcomes After Parental Cell Phone Exposure: Norwegian Mother/Child Prospective Study

Joel's comments:  The authors dismiss two outcomes associated with parental cell phone use during pregnancy. First, perinatal mortality was greater (with borderline significance) for expectant fathers whose testes were regularly exposed to cell phone radiation (relative risk = 1.77, 95% CI = 1.00 - 3.15) (or about 90 per 1,000 deaths vs. 50 per 1,000)  as compared to fathers with no exposure to the head or testes. Second, pregnant women were less likely to develop preeclampsia during pregnancy if the father's testes were regularly exposed to cell phone radiation (relative risk = 0.73, 95 % CI = 0.54 - 0.99) (or 2.7% vs. 3.7%) as compared to fathers with no exposure to the head or testes.

The study had several major weaknesses which may have contributed to the absence of other perinatal effects: the assessment of cell phone use relied on crude self-reported measures; cordless phone use was not assessed, and only a few potential confounders were examined. Moreover, there may have been few heavy cell phone users in the "high" exposure group in this prospective study.

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Prospective Study of Pregnancy Outcomes After Parental Cell Phone Exposure: The Norwegian Mother and Child Cohort Study

Baste V, Oftedal G, Møllerløkken OJ, Mild KH, Moen BE. Prospective Study of Pregnancy Outcomes After Parental Cell Phone Exposure: The Norwegian Mother and Child Cohort Study. Epidemiology. 2015 Apr 22. [Epub ahead of print]

Abstract

BACKGROUND: Research about prenatal exposure to electromagnetic fields from cell phones among expectant parents and reproductive outcome is limited. The aim of this article is to investigate the association between pregnancy outcome and parental cell phone exposure in a large prospective study.

METHODS: The study was based on the Norwegian Mother and Child Cohort Study conducted during the decade 1999-2009. In that study, pregnant women were recruited before a routine ultrasound examination during gestational week 15; they answered a questionnaire at that time and again around gestational week 30. The expectant father was invited to answer a questionnaire during gestational week 15 (2001-2009). The forms contained questions regarding cell phone use. The response rate was 38.7% and the cohort comprised 100,730 singleton births. Pregnancy outcomes were obtained by linkage to the Medical Birth Registry of Norway.

RESULTS: The risk of preeclampsia was slightly lower among women with medium and high cell phone exposure compared with low exposure after adjusting for potential confounders. Fathers with testis exposure when using cell phones had a borderline increased risk of perinatal mortality among offspring and a slightly decreased risk of partner developing preeclampsia during pregnancy compared with no cell phone exposure of head or testis. None of the other pregnancy outcomes was associated with cell phone exposure.

CONCLUSIONS: We found no association between maternal prenatal or paternal preconceptional cell phone exposure and any of the studied pregnancy outcomes. The only risk estimate suggesting a potential increased risk was not consistent with other findings.

http://1.usa.gov/1PwF38G

Excerpts

Brain cancer has been the main health concern regarding cell phone use due to the placement of the cell phone close to the head during calls, but other issues such as headache, concentration, and behavioral problems have also raised concern ... exposure of the brain regions of young children to radiofrequency electromagnetic fields can be 1.6 to three times higher than exposure of regions in adult brains ... there is no agreement about adverse health effects related to
radiofrequency fields at exposure intensities that do not cause a detectable increase in tissue temperature, except for reactions mediated by free radical pairs. Still, the IARC report states that it is likely that not all mechanisms of interaction between weak radiofrequency fields and biological structures have been discovered or characterized.

... Studies of cell phone exposure among pregnant women are sparse, but a few regarding behavioral problems in children after mothers’ cell phone use during pregnancy have been published.

Cell phone use and the possible effect on semen parameters have been studied among men attending fertility clinics. These studies suggest an association between prolonged cell phone use and adverse sperm motility, whereas results concerning other sperm parameters differed among the studies ...

Occupational studies among both men and women exposed to radiofrequency electromagnetic fields show some adverse reproductive outcomes, but the results are not homogeneous ...

The [Norwegian] cohort includes more than 100,000 pregnancies. Of the total number of invited women, 38.7% consented to participate ...The participation rate among fathers was 31.8% ...

Follow-up was conducted by linkage to the MBRN to obtain information about all pregnancies and offspring at birth. Only singleton births were included and the current database consists of 100,434 births with maternal information and 74,908 births with paternal information ...

Women who participated in the MoBa answered two questions regarding cell phone use in both gestational weeks 15 and 30. The questions were identical in the two questionnaires. The women were asked “How often do you talk on a cell phone?” and the options to respond were “Seldom/never,” “A few times per week,” “Daily,” and “On average more than 1 hour per day.” The second question was “Do you talk on your cell phone for longer than 15 minutes at a time?” and the response alternatives were “Never,” “Seldom,” and “Often.” These two questions were combined to reflect cell phone exposure as Low, Medium, and High ...

The expectant fathers answered a questionnaire at around week 15 of gestation. The questions regarding cell phone use were changed through different versions of the paternal questionnaire. Common to the different versions was the question regarding cell phone use before conception: “How often did you talk on a cell phone during the last 6 months before your partner got pregnant?” But the response alternatives differed between different versions of the questionnaires. In the first two versions (n = 41,397, 0.3% was set to missing due to no answer), the alternatives were “Seldom/never,” “A few times per week,” “Daily,” or “On average more than 1 hour per day.” For the last versions of the questionnaire (n = 33,511, 4.0% did not answer), the alternatives were “Less than once a week,” “1–2 times a week,” “3–6 times a week,” “1–4 times a day,” or “More than 5 times a day.”

For the two last versions of the questionnaire, four questions regarding current cell phone habits were also included. These questions were more detailed and were used as proxy for exposure before conception. The questions with response alternatives in parentheses were as follows: “Do you use a cell phone?” (“No” or “Yes”), “Do you use a ‘hands-free’ device?” (“Seldom/never,” “Only during longer calls,” or “Normally”), “If/when you use a ‘hands-free’ device, where do you mainly have the phone during the call?” (“In the trouser pocket in front,” “On the belt in front on the body,” “Other places on the body,” or “Away from the body”), and “How long do you talk on average in total on days with cell phone calls?” (“Less than 1 minute,” “1–10 minutes,” “11–30 minutes,” “31–60 minutes,” or “More than 60 minutes”).

Adverse reproductive outcomes analyzed were congenital malformation, perinatal mortality, low birth weight, preterm birth, small for gestational age (SGA), preeclampsia, abruptio placentae, and change in sex ratio ...

The analyses for maternal exposure were adjusted for maternal age, maternal smoking, and parity ...

This study includes the cohort of 100,231 births with information on maternal prenatal cell phone exposure; 15,139 (15%) of the pregnant women had high exposure to cell phone use [i.e., daily use] ...

The adjusted RR for adverse reproductive outcome after paternal cell phone exposure during the 6 months before conception showed similar risk estimates for low, medium, and high cell phone use (Table 6). Regarding paternal regular cell phone habits, exposure to the testes was associated with an increased risk of perinatal mortality among offspring and decreased risk of partner developing preeclampsia in pregnancy compared with no exposure to the head or testes ...
In this prospective study, we could not observe any association between maternal cell phone use during pregnancy and pregnancy outcomes: congenital malformation, perinatal mortality, low birth weight, preterm birth, SGA, abruptio placentae, or change in sex ratio. The results concerning preeclampsia suggested a reduced risk but this was not consistent with the other findings. We also did not find any clear and consistent association between the adverse pregnancy outcomes and paternal preconceptional cell phone use.

Maternal studies concerning pregnancy outcome related to cell phone use are scarce. We are aware of two case–control studies, both published in Chinese with abstracts available in English. The first study included 200 cases of early abortions and age-matched controls, and reported that after adjusting for risk factors, the multifactorial analysis revealed a significant association between mobile phone use and the risk for early spontaneous abortion.21 Another study by the same group used the same study design but with 138 cases of embryo growth ceasing as endpoint.22 The multifactorial analysis resulted in an association with the mother’s mobile phone use (OR = 6.0, 95% CI = 1.9, 18.9). The results of these studies are difficult to interpret, because only the abstracts are available. The mobile exposure information was self-reported and the risk of introducing recall bias is probably high because the information was obtained after the outcomes were known.

There have been some studies regarding behavioral problems in children after maternal cell phone use during pregnancy.4,5,28,29 In a study from the Danish National Birth Cohort,4 cell phone exposure was obtained from a questionnaire 7 years after birth. Based on this information, the authors found a higher risk of behavior problems after prenatal cell phone exposure; however, they wrote that the results should be interpreted with caution. In 2012, this group performed the same research on another group of participants in the Danish National Birth Cohort and they replicated their original findings 28 The same group of researchers also studied prenatal cell phone use and motor or cognitive/language developmental delays among infants at 6 and 18 months of age based on the same dataset in which where cell phone use was obtained 7 years subsequently; for these outcomes, the authors found no associations.29 Vrijheid and colleagues5 used data from a prospective birth cohort to examine the relation between cell phones use during pregnancy and neurodevelopment at 14 months of age, but found no association, nor was cell phone use related to the child’s sex, birth weight, or prematurity. The study was based on only 587 pregnancies.

Concerning paternal exposure, pregnancy outcome may be affected through an adverse effect on semen or sperm cells. Because distance to the phone is important for the radiofrequency exposure level, a potential direct effect is most likely when the cell phone is located close to the testes, whereas an indirect effect might occur if reproductive hormones are affected. In the latter case, head exposure must also be regarded. In our study, we could not observe any effect on reproductive outcomes irrespective of where the father usually held the emitting phone.

The main strength in this study is the prospective study design where cell phone exposure was collected before birth outcome. The challenge of gathering cell phone exposure data in epidemiologic settings has been an issue since the widespread use of cell phone began. Cell phone subscription information versus self-reported phone use as exposure proxies as well as changes in technology throughout the years have been discussed ... Radiofrequency exposure from
cordless phones could be important but unfortunately we did not have such information. We also had no information about whether a cell phone was turned on when it was carried in the pocket or on the belt, but in this situation the radiofrequency exposure has been shown to be negligible.

We could not reveal any association between maternal cell phone use during pregnancy, nor could we find any association between paternal preconceptional cell phone use and any of the pregnancy outcomes researched in this study.


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Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley

Electromagnetic Radiation Safety

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