A researcher who revealed a boom in the birth of boys nine months after SA hosted the Soccer World Cup in 2010 has done it again ... but this time the backdrop of his finding is less uplifting.
Three months after the start of the Covid epidemic in SA, and for the only time in 100 months analysed, more girls than boys were born, according to Gwinyai Masukume, formerly of the Wits University school of public health.
The statistically significant shift in the “sex ratio at birth” for June 2020 suggests the onset of the pandemic engendered population stress with notable effects on pregnancy and public health, said Gwinyai Masukume, from the academic paediatrics department at the Mater Dei Hospital medical school in Malta.
In a preprint of a paper written with colleagues in Malta, Dublin and Johannesburg, Masukume said the long-term sex ratio at birth approximates 0.51 with a slight male excess, meaning 51 out of every 100 babies born are male.
Last June, when historical data suggested the ratio should be 0.504 it was 0.499, the only time it inverted in the 100 months Masukume and his team analysed.
This was in line with observations after sudden unexpected stress events which reduce the survival rate of male foetuses.
For example, the same effect was seen in the UK between four and five months after the car-crash death of Princess Diana and after a 10-day war in Slovenia in 1991.
Earlier work by Masukume also found a reduction in the sex ratio at birth between three and five months after the 2011 attacks in Norway when Anders Behring Breivik killed 77 people; the 2012 Sandy Hook Elementary School shooting in Connecticut, US, when Adam Lanza killed 26 people; the US terror attacks on September 11 2001; and terrorist bombings in Madrid and London in 2004 and 2005.
“Such stressful life events impact on maternal neuroimmunoendocrine condition; male foetuses are more vulnerable to such changes in condition,” said Masukume.
The US health agency March of Dimes says in a briefing document: “Maternal stress has been associated with poor birth outcomes including preterm birth, infant mortality and low birthweight.
“Stress results in increases in cortisol, norepinephrine and inflammation, which affect the fetal environment and have implications for maternal and infant health.”
Masukume and his colleagues examined data from Stats SA on 8,151,364 births between September 2012 and December 2020, when the overall sex ratio was 0.505.
The 84,131 live births in June 2020 comprised 42,022 boys and 42,109 girls, which proved the team’s primary hypothesis of a decrease in the sex ratio at birth between three and five months after SA’s first Covid case on March 5, its first death on March 27 and the imposition of a national state of disaster and a hard lockdown.
“In short, March 2020 was a momentous month in relation to Covid-19 in SA,” said Masukume.
The timing of the dip suggests a mechanism operating in ongoing pregnancies whereby, due to stress, there is an elevated risk of foetal death among males, resulting in fewer live-born males.
A secondary hypothesis that the sex ratio at birth would decrease nine months later in December 2020 — as it did, for example, after the 1995 Kobe earthquake in Japan, which killed more than 6,000 people — was not borne out. The month’s sex ratio at birth was 0.503.
“Our findings are consistent with studies that have reported a transient sex ratio at birth decline three to five months after unexpected events which stressed populations acutely and severely,” said Masukume.
“The timing of the dip suggests a mechanism operating in ongoing pregnancies whereby, due to stress, there is an elevated risk of fetal death among males, resulting in fewer live-born males.
“Beyond the direct adverse effects of the pandemic pathogen on pregnant women, evidenced by a higher maternal mortality rate among women admitted with SARS-CoV-2 infection, anxiety and stress likely generated by news of the impending pandemic ... led to disproportionate male fetal loss in June 2020.
“Triangulation with antepartum deaths from SA’s perinatal mortality audit system, when the data becomes publicly available, would be needed to directly confirm this excess male fetal loss.”
Masukume said the June 2020 decline could plausibly have been due to xenophobic riots in Johannesburg in September 2019, which claimed 12 lives. But it was doubtful in light of precedents such as a change in the sex ratio at birth in Los Angeles after riots sparked by the police beating of Rodney King “during the three to five month post-event window”.
“Second, similar [xenophobia-related] protests/riots have occurred before in SA during the most recent 100-month period, in April 2015, but with no significant sex ratio at birth decline either three to five or nine months later.
“Third, contrary to Covid-19, which had broader nationwide ramifications, these protests were confined to certain locations with possibly more localised effects.”
Masukume’s 2010 World Cup study found the ratio of boys born nine months after the event — 0.5063 — was the highest recorded between 2003 and 2014.
“The World Cup caused less stress. People were happier. There has been published research done that people had better feelings, positive feelings about themselves and their country. People also probably had more sexual intercourse during the World Cup,” Masukume said at the time.
“It has been known that if people have sexual intercourse more frequently there is a tendency to have more boys born than girls.”
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